6.2 0 Td <7665> Tj 5.6 0 Td <6C> Tj 6.2 0 Td <20> Tj 5.6 0 Td <68> Tj 2.8 0 Td <2F> Tj Q 6.1 0 Td <69> Tj 6.1 0 Td <77> Tj We used rainbow cable to wire the potentiometers from the front panel to the PCB. 49.6 351.4 Td /F3 11 Tf <48> Tj 6.1 0 Td <63> Tj If you’re just using a USB tester all you need to do is disconnect the tester and place it into a USB socket to find the maximum capacity which they record. 3.1 0 Td <7465> Tj 6.1 0 Td <69> Tj Now we have a baseline for what the load is capable of dissipating, let’s demonstrate its use by using it to do a variety of different tasks we often find ourselves doing. Q 1 1 1 rg 7.4 0 Td <20> Tj 6 0 Td <75> Tj You can use this dummy load to simulate the load on the power supply circuit under different load conditions, to monitor the temperature curve in relation to load. 3 0 Td <6E> Tj 3.9 0 Td <65> Tj 6.3 0 Td <63> Tj 7.9 0 Td <73> Tj 6 0 Td <70> Tj 4.8 0 Td <20> Tj 6.1 0 Td <75> Tj 16 0 Td <6F> Tj 5.6 0 Td <66> Tj 4.4 0 Td <6D> Tj 6.1 0 Td <6D> Tj 6.8 0 Td <20> Tj BT q 0 0 0 rg 6.2 0 Td <6E> Tj Q 3 0 Td <73> Tj This unit provides a 50 Ohm resistive load to any transmitter operating from 1.8Mhz thru 200MHz. 6.7 0 Td <69> Tj 3.6 0 Td <77> Tj 4.3 0 Td <20> Tj 6.4 0 Td <20> Tj Q 7.3 0 Td <61> Tj 6 0 Td <61> Tj 4.3 0 Td <61> Tj 49.6 283.4 Td /F1 11 Tf <65> Tj 6.2 0 Td <65> Tj 2.5 0 Td <67> Tj q 0 0 0.50196 rg 5.5 0 Td <6D> Tj If this voltage is greater than the reference voltage from the potentiometer the op-amp will shutoff voltage to the gate of the MOSFET, which will also stop the current flowing to the shunt resistor. 3.4 0 Td <30> Tj If you feel your wiring getting warm under load, use thicker or better-quality wire. 7.2 0 Td <77> Tj 3 0 Td <6D> Tj 6.1 0 Td <66> Tj 4.2 0 Td <6E> Tj The power limiting circuit is based on a simple analog multiplier (circuit around U8). Both supplies reacted nearly identically when a 1A load was quickly applied to them by using the load switch. 3.3 0 Td <75> Tj 2.4 0 Td <6E> Tj 6.1 0 Td <65> Tj 4 0 Td <7468> Tj q 0.27843 0 0.72156 rg 6.1 0 Td <72> Tj 4 0 Td <7265> Tj 5.4 0 Td <75> Tj 4.3 0 Td <6E> Tj 7.9 0 Td <75> Tj They all follow a very similar design; they all use a combination of load resistors/current shunts to detect the current, a MOSFET to control the current, and a way to pull the heat away from the MOSFET as it dissipates the power. 41.4 0 Td <6E> Tj 6.2 0 Td <722C> Tj 5.5 0 Td <72> Tj 6.7 0 Td <67> Tj 3.6 0 Td <74> Tj 9.7 0 Td <7369> Tj Arduino DC Electronic Load Circuit Diagram In the below schematic, the operational amplifier has two sections. 2.4 0 Td <6C73> Tj 6.1 0 Td <6C61> Tj 6.1 0 Td <66> Tj 6.7 0 Td <63> Tj 7.9 0 Td <65> Tj 3.6 0 Td <75> Tj 9.1 0 Td <2E> Tj 7.9 0 Td <68> Tj 5.5 0 Td <3A> Tj 3.7 0 Td <6E> Tj 6.1 0 Td <79> Tj 6.1 0 Td <6E> Tj 2.8 0 Td <6F> Tj 9.9 0 Td <20> Tj 3.4 0 Td <6C61> Tj 6.1 0 Td <20> Tj 6.1 0 Td <72> Tj 6.7 0 Td <20> Tj 6 0 Td <2C> Tj 6.1 0 Td <20> Tj 2.8 0 Td <44> Tj 5.6 0 Td <72> Tj We then set the printer to print from 0mm to 2.5mm in white. 1 0 obj 3.2 0 Td <6A> Tj 2.4 0 Td <6E> Tj 6.1 0 Td <65> Tj 17.3 0 Td <75> Tj 3.7 0 Td <2E> Tj Q 5.8 0 Td <20> Tj 3.1 0 Td <7468> Tj 3.2 0 Td <6E> Tj You can also check the video at the bottom of this page which explains the complete working of the circuit. 6.1 0 Td <65> Tj 6.2 0 Td <2074> Tj 6.1 0 Td <61> Tj 6.1 0 Td <6C> Tj 6.1 0 Td <726F> Tj 2.8 0 Td <66> Tj 3 0 Td <68> Tj 4.3 0 Td <7468> Tj ET We were quite surprised by the results of this test. 3.1 0 Td <73> Tj 7.3 0 Td <20> Tj 5.1 0 Td <70> Tj Q 5.5 0 Td <74> Tj 6.1 0 Td <206F> Tj We can then use this to compare against other similarly rated supplies. 6.1 0 Td <20> Tj 6.7 0 Td <20> Tj 2.4 0 Td <72> Tj 5.8 0 Td <20> Tj 5.6 0 Td <67> Tj /BitsPerComponent 8 5.6 0 Td <20> Tj 6.6 0 Td <20> Tj 6.1 0 Td <6E> Tj 2.5 0 Td <73> Tj Therefore, the 1.3Ah rating only exists when the current draw is 65mA. 6.1 0 Td <64> Tj �ak�Έv�_W�����#Y���x��#x�K����9��Gp$�:��Ü�sX��.��2�K\NTw޷�۝�砬��d�=9��6\aΊ3����HW���U� 3.1 0 Td <20> Tj 5.6 0 Td <67> Tj 2.7 0 Td <73> Tj 5.8 0 Td <7468> Tj BT 6.1 0 Td <74> Tj 6.1 0 Td <6F> Tj 2.8 0 Td <20> Tj 3.3 0 Td <6F> Tj 6.2 0 Td <65> Tj BT 8.5 0 Td <65> Tj 49.6 468.3 Td /F3 11 Tf <6E> Tj BT 6.3 0 Td <20> Tj 11.6 0 Td <6C> Tj BT 8.6 0 Td <75> Tj 6.1 0 Td <6C65> Tj Each side will take about 5 hours to print at these settings. Conventional mosfets can be used but you would be limiting the range of voltages/loads the Dummy Load would be able to cover due to running the mosfet in it's linear mode. << 6.1 0 Td <73> Tj 4.9 0 Td <20> Tj 4 0 Td <61> Tj 6.1 0 Td <63> Tj 6.1 0 Td <65> Tj 6.1 0 Td <74> Tj 6.7 0 Td <65> Tj 2.8 0 Td <20> Tj 6.2 0 Td <65> Tj 2.8 0 Td <66> Tj 6.1 0 Td <61> Tj 9.4 0 Td <20> Tj q 0.13725 0 0.86274 rg 3.6 0 Td <65> Tj 4.6 0 Td <20> Tj /Im3 Do Q 6.1 0 Td <64> Tj 6.1 0 Td <7421> Tj 6.1 0 Td <2032> Tj ET 2.4 0 Td <6C7374> Tj Q This, in turn, saturates the gate of the MOSFET, which allows current to flow from the MOSFETs Drain to the source. 6.1 0 Td <6E> Tj 5.5 0 Td <4A> Tj Q 7.4 0 Td <20> Tj BT ET 6.1 0 Td <74> Tj 2.7 0 Td <30> Tj You don't need to pollute the airwaves while just tuning or testing your transmitter! This switch will allow us to quickly remove or apply the load from a circuit, which can be very useful to analyse overshoot as we will show later. Q 0 0 0 rg 3.1 0 Td <75> Tj 8 0 Td <6F> Tj 5.6 0 Td <20> Tj 6.7 0 Td <6F> Tj Q q 423.6 609.5 120.5 170.1 re W* n q 0 0 0 rg 4 0 Td <737973> Tj 6.1 0 Td <6E> Tj 8.6 0 Td <72> Tj 6.2 0 Td <4E> Tj 6.2 0 Td <72> Tj 4.9 0 Td <63> Tj 8.7 0 Td <20> Tj 9.1 0 Td <70> Tj 3.7 0 Td <68> Tj 2.4 0 Td <73> Tj 6.8 0 Td <6B> Tj 6.2 0 Td <6E> Tj q 0 0 0 rg 8.6 0 Td <6F> Tj 5.6 0 Td <20> Tj 7.3 0 Td <75> Tj 6.1 0 Td <65> Tj An electronic load, also known as a constant current dummy load, is a device design so a power supply can draw a certain amount of current without dissipating too much of heat. 6.1 0 Td <65> Tj 5.5 0 Td <68> Tj 6.1 0 Td <64> Tj 6.7 0 Td <61> Tj q 0.13725 0 0.86274 rg 5.5 0 Td <7265> Tj The other side of this header needs to be wired to the power switch. q 0 0 0 rg 6.1 0 Td <68> Tj 2.4 0 Td <74> Tj 7.3 0 Td <20> Tj 6.1 0 Td <7365> Tj 5.6 0 Td <30> Tj 2.7 0 Td <46> Tj 6.1 0 Td <75> Tj Q 14.3 0 Td <20> Tj 9.1 0 Td <6E> Tj Which is shown in the datasheet here. 2 0 obj 3 0 Td <73> Tj 5.5 0 Td <64> Tj i.e. 6.8 0 Td <2C20> Tj 6.7 0 Td <75> Tj 6.1 0 Td <72> Tj 7.3 0 Td <20> Tj 5.5 0 Td <69> Tj BT 1, so no PCB design is provided. 7.9 0 Td <61> Tj q 0 0 0 rg 6.1 0 Td <72> Tj 49.6 201.8 Td /F3 11 Tf <49> Tj IXYS ‘ Linear L2™ MOSFETs) which is specifically designed to operate in linear region with an extended FBSOA. 6.1 0 Td <7265> Tj 4.9 0 Td <77> Tj A Darlington pair is used to provide high impedance input since we want to use a low wattage potentiometer to vary the loading. 6.5 0 Td <20> Tj 6.1 0 Td <65> Tj 49.6 392.1 Td /F3 11 Tf <77> Tj 9.7 0 Td <65> Tj 3.7 0 Td <68> Tj 8 0 Td <69> Tj 195.8 796.7 Td /F1 10 Tf <53> Tj 3.6 0 Td <65> Tj 6.1 0 Td <6E> Tj 6.1 0 Td <66> Tj 5.5 0 Td <6F> Tj BT This is fed into a comparator along with a control voltage that is set by a variable resistor. 6 0 Td <61> Tj 3 0 Td <68> Tj 3.1 0 Td <6E> Tj 2.7 0 Td <31> Tj 5.5 0 Td <69> Tj 6.7 0 Td <74> Tj 3.2 0 Td <64> Tj 6.1 0 Td <65> Tj We highly recommend you use either a raft or brim on the bottom half to reduce the warping. 9.1 0 Td <61> Tj 3.1 0 Td <20> Tj 4.7 0 Td <6F> Tj 2.4 0 Td <6F> Tj 3.1 0 Td <6C64> Tj This is about the size of your typical old school home radiator and is rated for “2kW continuous.” It’s $2923 in the Bird Online Store, but can often be found used on eBay for less. 6.1 0 Td <6D> Tj BT 6.2 0 Td <20> Tj 7 0 Td <20> Tj 2.9 0 Td <20> Tj The files are available on the resources section of our website. 49.6 147.6 Td /F3 11 Tf <72> Tj 7.2 0 Td <6F> Tj 4.7 0 Td <20> Tj 6 0 Td <72> Tj 9.1 0 Td <32> Tj q 0 0 595.4 842 re W* n Since our lead-acid battery has a rating of 1.3Ah we can expect a test time of around: This means, if we record the voltage every 15 mins for two and a half hours, we should capture the full range of the battery from fully charged to fully discharged. It’s worth mentioning that in an enclosed space the temperature is not linear. 49.6 741.3 Td /F2 24 Tf <45> Tj 14.7 0 Td <6164> Tj ET 7 0 Td <20> Tj 7.1 0 Td <20> Tj 9.4 0 Td <20> Tj 3 0 Td <64> Tj 3.3 0 Td <76> Tj 6.1 0 Td <77> Tj 6.7 0 Td <61> Tj 6.1 0 Td <6F> Tj ET 9.2 0 Td <6974> Tj 6.6 0 Td <20> Tj 3.6 0 Td <61> Tj 4.2 0 Td <72> Tj 6.1 0 Td <72> Tj q 0 0 0 rg 5.5 0 Td <30> Tj 5.5 0 Td <69> Tj 2.8 0 Td <2D> Tj 3.1 0 Td <20> Tj Q 11 0 Td <20> Tj 6.1 0 Td <7369> Tj 6.7 0 Td <73> Tj 4 0 Td <20> Tj 6.1 0 Td <75> Tj 2.7 0 Td <32> Tj 3.4 0 Td <73> Tj BT ���������/��J����+�����H-5�_�#���{����CȦ���K��P��7��,�oi�����p99��{�t����aްI�ӧۯ���D海����l�����…m��D�����y���\/�Rw�I�#��KbT}�Mڻ�8�B�u'�!�����iD�7�W�!ܻ�ak�'����3.W{���'Z�lc�9~���}�;�~_JI�����?�����i{�[��M�9�R|9f���v6�p�M�@~%\���O�윌�2��u����{�y�qI}��e�8aj������՗�E"���.�zS���v� 6.1 0 Td <6E> Tj 6.1 0 Td <6E> Tj 2.4 0 Td <7320> Tj 4.2 0 Td <75> Tj 6.1 0 Td <696F> Tj 5.5 0 Td <74> Tj 6.1 0 Td <6374> Tj 6.1 0 Td <65> Tj 6.1 0 Td <72> Tj 5.5 0 Td <746C65> Tj 6.1 0 Td <65> Tj 6.7 0 Td <20> Tj 8.5 0 Td <70> Tj Q 4.2 0 Td <61> Tj ET 9.8 0 Td <6973> Tj 2.4 0 Td <65> Tj 5.4 0 Td <75> Tj /Subtype/Image 5.6 0 Td <75> Tj 7.3 0 Td <20> Tj 6.7 0 Td <6C> Tj 7.3 0 Td <65> Tj ET 6.1 0 Td <72> Tj 3.3 0 Td <5365> Tj 2.8 0 Td <50> Tj 7.3 0 Td <61> Tj 3.7 0 Td <6F> Tj BT 6.1 0 Td <74> Tj 6.8 0 Td <65> Tj 8.4 0 Td <20> Tj 7.9 0 Td <6F> Tj 8.4 0 Td <20> Tj q 0 0 0 rg 6.1 0 Td <66> Tj 3.1 0 Td <6F> Tj 6 0 Td <77> Tj 6.1 0 Td <64> Tj << 9.7 0 Td <20> Tj 5 0 Td <72> Tj 3.1 0 Td <75> Tj These are N-type Linear Power Mosfets, the IXTK46N50L (500v, 46A). 6.1 0 Td <6E> Tj 3.1 0 Td <65> Tj 6.7 0 Td <65> Tj 7.9 0 Td <65> Tj 6.2 0 Td <2C> Tj 3.3 0 Td <44> Tj 3.6 0 Td <65> Tj 5.6 0 Td <20> Tj 3.1 0 Td <6F> Tj 6.1 0 Td <65> Tj 6.2 0 Td <61> Tj 6.1 0 Td <69> Tj We then want to measure the current and voltage. 6.1 0 Td <6E> Tj q 0.27843 0 0.72156 rg 3 0 Td <77> Tj 3.3 0 Td <20> Tj 5.6 0 Td <20> Tj 6.7 0 Td <72> Tj 2.4 0 Td <6E> Tj q 0 0 0 rg 6.2 0 Td <61> Tj A dummy load is essential for testing amplifiers, and although there is really very little involved, setting one up properly (and cheaply) can become irksome. Q 3.9 0 Td <7375> Tj For all the wire connections, excluding the potentiometers and input from the power supply under test, we used male and female pin header connectors to allow for easy placement. 6 0 Td <6E> Tj 6.7 0 Td <79> Tj ET 6.7 0 Td <70> Tj 3.3 0 Td <73> Tj 6.7 0 Td <77> Tj 4 0 Td <766F> Tj q 0 0 0.50196 rg Another interesting use for an electronic load is to test and compare the performance of power supplies. The PCB was designed in the new Eagle version 9.3.0 using the standard libraries. 11.6 0 Td <75> Tj 9.1 0 Td <6F> Tj 7.9 0 Td <61> Tj 3.1 0 Td <61> Tj A circuit that has been aligned under this condition would be out of alignment when a normal external antenna is connected. Q 6.1 0 Td <75> Tj 6.2 0 Td <30> Tj Variable Dummy Load Circuit Schematic Diagram. 7.2 0 Td <2E> Tj q 0 0 0 rg Let’s assume you have a 12V power supply and need to step the voltage down to 5V using a voltage regulator. 7.3 0 Td <6F> Tj BT 3.1 0 Td <62> Tj 6 0 Td <64> Tj 11 0 Td <6F> Tj 6.1 0 Td <20> Tj 2.5 0 Td <63> Tj 2.8 0 Td <53> Tj 6 0 Td <65> Tj 5 0 Td <63> Tj 6.2 0 Td <73> Tj 2.8 0 Td <6F> Tj 6.1 0 Td <20> Tj ET We then attach the load to the battery with the multimeter in parallel to measure the voltage. 4.2 0 Td <74> Tj 5.5 0 Td <69> Tj 5.6 0 Td <65> Tj 2.8 0 Td <20> Tj It sounds simple enough, but there are two main problems. 6 0 Td <30> Tj 2.9 0 Td <20> Tj 6.2 0 Td <69> Tj 49.6 791.5 496.1 1 re f* The LED was placed in the front panel and the wiring was extended from the PCB. 16.5 0 Td <74> Tj 7.1 0 Td <20> Tj 5.4 0 Td <69> Tj 14.7 0 Td <72> Tj 6 0 Td <72> Tj Here is the schematic diagram of the circuit. 14.7 0 Td <5620> Tj 6.2 0 Td <2065> Tj 5 0 Td <74> Tj 5 0 Td <61> Tj 6.1 0 Td <7265> Tj 49.6 134.1 Td /F3 11 Tf <63> Tj q 194.9 0 0 226.6 329 95 cm 6.1 0 Td <6B> Tj 3 0 Td <77> Tj 3.3 0 Td <61> Tj 7.2 0 Td <20> Tj 2.4 0 Td <64> Tj ET In reality, the two devices behaved near identically. 4.2 0 Td <6F> Tj In this setup, our circuit was only able to dissipate about 15W drawing a maximum current of 1.25A at 12V. 6.1 0 Td <72> Tj 3.6 0 Td <7465> Tj 10.6 0 Td <6D> Tj 5.5 0 Td <73> Tj 5.6 0 Td <2E> Tj Let’s say, for example, you have a 12V lead acid battery that you want to use for a project but have no idea how of its actual capacity. 5.3 0 Td <61> Tj 5.4 0 Td <74> Tj 6.1 0 Td <73> Tj The voltage applied to R23 is controlled by the enable/disable switch and by the power limiting circuit. 6.1 0 Td <64> Tj 4 0 Td <65> Tj 3.3 0 Td <20> Tj 6 0 Td <77> Tj There is a class of so called linear MOSFET (e.g. 3.6 0 Td <63> Tj The direction of travel is different however. Q 3 0 Td <61> Tj Breadboard and prototyping hardware is also required. 4.2 0 Td <2062> Tj We can use this device to test the circuit in a real-world application. 5.6 0 Td <2C> Tj 7.9 0 Td <6F> Tj 7 0 Td <20> Tj 6.1 0 Td <6E> Tj This circuit has 3 inputs: Vx (Vin), Vy (Iin) and Vw (constant divisor). 6.7 0 Td <3A> Tj 9.2 0 Td <61> Tj 3.4 0 Td <62> Tj 7.9 0 Td <6974> Tj 6.7 0 Td <6F> Tj 6.1 0 Td <65> Tj 7.5 0 Td <20> Tj 5.5 0 Td <7320> Tj 5.4 0 Td <6F> Tj 9.1 0 Td <6974> Tj The load will apply a constant drain of your chosen range to the battery bank, until the bank cutoff voltage is reached and the battery bank shuts down. Q We have designed an enclosure for you to print yourself. 4.5 0 Td <20> Tj 49.6 174.7 Td /F3 11 Tf <63> Tj 6.1 0 Td <20> Tj This produced the base of the panel as shown here. 4.2 0 Td <20> Tj 5.5 0 Td <61> Tj The rubber feet should help reduce noise and vibration being transferred to the desk or bench. 3.6 0 Td <6973> Tj 6.4 0 Td <6973> Tj 8.6 0 Td <73> Tj 6 0 Td <7665> Tj 6.2 0 Td <73> Tj Of course, they also have a way for the user to select the desired current. 2.4 0 Td <73> Tj 6.7 0 Td <20> Tj 6.2 0 Td <7465> Tj 2.8 0 Td <68> Tj 5.6 0 Td <65> Tj Another potential use for this device is to test the performance of a power supply under specific situations. 6.1 0 Td <6E> Tj 2.5 0 Td <73> Tj 8.5 0 Td <65> Tj 6.1 0 Td <73> Tj 4.2 0 Td <6F> Tj q 0 0 0 rg 6.7 0 Td <5F> Tj 6.7 0 Td <72> Tj q 0.13725 0 0.86274 rg 6.1 0 Td <67> Tj 4.8 0 Td <20> Tj 7.8 0 Td <20> Tj 2.4 0 Td <73> Tj 6 0 Td <6E> Tj 3.3 0 Td <65> Tj 6.1 0 Td <6E> Tj 3.4 0 Td <64> Tj 6.1 0 Td <6E> Tj 6.2 0 Td <20> Tj 11.6 0 Td <75> Tj You can use this dummy load to simulate the load on the power supply circuit under different load conditions, to monitor the temperature curve in relation to load. 6 0 Td <65> Tj 6 0 Td <20> Tj To do this, we simply need to connect the constant current load to a power supply and dial in the smallest load value we can. 5.5 0 Td <75> Tj 3.9 0 Td <6F> Tj However, what if you have a dynamic load or a voltage supply that changes over time such as a battery? 2.8 0 Td <62> Tj 6.1 0 Td <65> Tj 11.6 0 Td <6C6F> Tj 3.6 0 Td <67> Tj 6.4 0 Td <20> Tj 6.6 0 Td <68> Tj 6.1 0 Td <65> Tj 6.1 0 Td <20> Tj 9.4 0 Td <20> Tj 3.3 0 Td <6B> Tj 7.1 0 Td <20> Tj * Quantity shown, may be sold only in packs. 6.1 0 Td <67> Tj 6 0 Td <6E> Tj Q 2.4 0 Td <73> Tj BT .�0"�p1⥾i����G����iO˘���Z�|�s\ ~;7�C��$GO��=����n6�˗���?��p����;O{�.J���K_%���/�&������0�R����~9��o�ѵއ�g��o�Z׷�_b��?܄���iu)�����ט_'��3��j�O!9Wz��t�2��`Ѹ�}29s}��r�e���ݿ���9�-� 5.5 0 Td <75> Tj 3.8 0 Td <70> Tj 7.2 0 Td <20> Tj 5.6 0 Td <2F> Tj 7.3 0 Td <20> Tj q 0 0 0 rg 3.2 0 Td <7375> Tj 6.7 0 Td <50> Tj 6.2 0 Td <65> Tj 7.9 0 Td <20> Tj It was printed in two pieces both being positioned flat on the build surface. 5.6 0 Td <72> Tj 3 0 Td <65> Tj 6.8 0 Td <72> Tj 49.6 269.8 Td /F3 11 Tf <74> Tj 6 0 Td <69> Tj 9.1 0 Td <69> Tj 6.1 0 Td <7874> Tj With that said, you will still need to keep the power draw on this device to under 3W or so because the components can overheat without adequate cooling, and the breadboard itself isn't designed to handle high currents for too long without causing damage. 6.1 0 Td <66> Tj 5.8 0 Td <20> Tj 7.9 0 Td <75> Tj 5.6 0 Td <2C20> Tj 2.8 0 Td <20> Tj 8.7 0 Td <75> Tj 6.1 0 Td <74> Tj 2.4 0 Td <6C> Tj 9.2 0 Td <69> Tj 2.8 0 Td <45> Tj 6.2 0 Td <75> Tj 3 0 Td <65> Tj BT 3.1 0 Td <74> Tj 2.8 0 Td <77> Tj 6.1 0 Td <61> Tj BT 3.1 0 Td <65> Tj 3 0 Td <75> Tj 6.1 0 Td <6D> Tj Q 3.1 0 Td <68> Tj 14.7 0 Td <72> Tj 6.1 0 Td <64> Tj 6.7 0 Td <70> Tj 4.4 0 Td <70> Tj ET ET 6.1 0 Td <72> Tj 8.6 0 Td <6F> Tj 5.3 0 Td <61> Tj 3.9 0 Td <20> Tj 7.9 0 Td <41> Tj 6.1 0 Td <73> Tj 518.5 333 0.1 213.4 re f* 3.2 0 Td <7265> Tj The Apple charger slightly ahead, due to its slightly lower ripple and slightly faster-switching speed. 4.2 0 Td <20> Tj 6.1 0 Td <2C> Tj 6.1 0 Td <74> Tj 5.4 0 Td <72> Tj 2.8 0 Td <54> Tj 5.5 0 Td <70> Tj 4.2 0 Td <79> Tj 7 0 Td <20> Tj 8.2 0 Td <20> Tj 6.1 0 Td <61> Tj 6.6 0 Td <76> Tj We then set the potentiometers on the breadboard to find the maximum power dissipation obtainable, which we measured on the Unit-T UT804 bench multimeter. 8.4 0 Td <20> Tj ������YWP�;b������/����\Xh����=������������E�����}���}�do�m���Dž*������ 6.5 0 Td <20> Tj 5.5 0 Td <69> Tj 9.1 0 Td <65> Tj 3.1 0 Td <20> Tj We can use our constant current load to verify that the device is capable of delivering the claimed current, and we can use an oscilloscope to monitor the voltage ripple at this load. 8 0 Td <65> Tj 9.8 0 Td <6F> Tj 4.3 0 Td <65> Tj 6.1 0 Td <63> Tj 3 0 Td <206C> Tj Q 8.6 0 Td <6E> Tj 3.1 0 Td <7469> Tj 6.1 0 Td <74> Tj 7.9 0 Td <20> Tj 7.3 0 Td <6A> Tj 7.4 0 Td <2E> Tj 7.9 0 Td <65> Tj 4.9 0 Td <20> Tj 2.4 0 Td <6E> Tj Using a constant current load while testing the device enabled us to take voltage readings of the device under constant current load to calculate the power output. 49.6 481.9 Td /F3 11 Tf <61> Tj 4 0 Td <61> Tj 6.2 0 Td <696E> Tj This experiment allows us to analyse the temperature increase of an 7805 linear voltage regulator as we increased the current demands on the circuit. 11.2 0 Td <20> Tj This kind of dummy load is widely used in testing power supply. Following some inspiration from both Dave Jones' and Martin Lorton's sites, I decided I will build a constant current dummy load. 3.4 0 Td <796F> Tj 6.1 0 Td <70> Tj 2.8 0 Td <7665> Tj But, as with all things RF, details matter. Circuit topologies. 5.8 0 Td <76> Tj 3.4 0 Td <30> Tj If you intend to test the breadboard prototype with high current, use thicker and shorter connections to improve the current handling capabilities. 9.2 0 Td <6D> Tj 11.6 0 Td <6E> Tj 6.1 0 Td <67> Tj 8 0 Td <20> Tj 6.7 0 Td <67> Tj ET 6.7 0 Td <6E> Tj 6.1 0 Td <69> Tj Q Assemble three sets of resistor banks using back-to-back general-purpose PCBs as shown in Fig. A 'Brute Force' 15 Amp Power (Dummy-) Load. 6.7 0 Td <20> Tj 6.2 0 Td <7272> Tj 3.2 0 Td <73> Tj 5.5 0 Td <74> Tj 6.7 0 Td <21> Tj 7 0 Td <20> Tj This would help avoid the need to first attach the device with a multimeter in series to dial in the desired current. 6.1 0 Td <75> Tj All that's involved is a bunch of 3.9 ohm 10W resistors, which can be cooled using a variety of methods. 6.1 0 Td <77> Tj 3.7 0 Td <68> Tj 4.3 0 Td <54> Tj Some modification may be required to the enclosure if you purchase your components from an alternate supplier. 6.1 0 Td <6C> Tj 5 0 Td <61> Tj 3.7 0 Td <70> Tj 5.5 0 Td <65> Tj 5.1 0 Td <2F> Tj 5.4 0 Td <75> Tj 9.2 0 Td <69> Tj ET 6.4 0 Td <20> Tj 6.1 0 Td <72> Tj ET 6.2 0 Td <62> Tj SMA Male 50 Ohm 6GHz RF Coaxial Termination Dummy Load x1 FPV VTX Gold plated. 7.9 0 Td <68> Tj 5.6 0 Td <63> Tj 9.2 0 Td <6F> Tj q 0 0 0 rg ET Q 2.8 0 Td <32> Tj 4.9 0 Td <61> Tj 7.9 0 Td <73> Tj Q 6.1 0 Td <75> Tj The circuit for a dummy load is stupid (heh) simple - it's literally just a 50-ohm resistor across the antenna connector's inner conductor and shield. q 0 0 0 rg 4.1 0 Td <6F> Tj Q 6 0 Td <65> Tj This switch will allow us to remove power to the device itself. 4.9 0 Td <72> Tj 6.8 0 Td <72> Tj 6.1 0 Td <65> Tj 3.7 0 Td <7465> Tj 3.6 0 Td <2075> Tj 6.7 0 Td <20> Tj q 0 0 0 rg 5.5 0 Td <6E> Tj 3.7 0 Td <74> Tj You could add an LCD readout to display the voltage and current, and calculate the power/capacity of the device under test. 49.6 523.1 Td /F3 11 Tf <41> Tj 6.1 0 Td <20> Tj 8.6 0 Td <68> Tj 7.4 0 Td <20> Tj 3.1 0 Td <20> Tj 6.2 0 Td <6E> Tj 5.5 0 Td <6F> Tj 6.2 0 Td <76> Tj 6.7 0 Td <64> Tj 6.1 0 Td <72> Tj This didn't make sense initially, until we remembered that it is industry standard for lead-acid batteries to have discharge and charge ratings based on a 20 hour period. 6.1 0 Td <7473> Tj In this situation, the two supplies were both on par. 6.1 0 Td <72> Tj 6.1 0 Td <7272> Tj 523.9 94.9 0.1 226.8 re f* The load current is set by a 10 turn potentiometer (R23). 2.4 0 Td <6E> Tj 49.6 710.4 Td /F2 24 Tf <50> Tj 5.5 0 Td <20> Tj We printed our enclosure using Flashforge white filament on a Flashforge Creator Pro at 200-micron layer height. 4.3 0 Td <20> Tj 5.6 0 Td <65> Tj 5.8 0 Td <73> Tj 4.3 0 Td <74> Tj 5.4 0 Td <666F> Tj 7.2 0 Td <20> Tj 6.1 0 Td <6C79> Tj 7.2 0 Td <20> Tj Note: We can see the operational amplifier has a certain lag before it can detect the differential voltage across its input pins, resulting in signal above. 6.2 0 Td <73> Tj 334.3 333 184.3 213.4 re f* 5.5 0 Td <69> Tj 3.9 0 Td <6361> Tj 6.8 0 Td <6D> Tj You then need to dial in the desired current using the current display on the multimeter or the USB tester. 11.9 0 Td <20> Tj Take care though, as the lack of solder mask can make soldering some components a little tricky. 3.5 0 Td <68> Tj Hook up wire, cable ties and 3mm mounting hardware is also required. ET 5 0 Td <61> Tj 6.7 0 Td <5375> Tj 3.4 0 Td <61> Tj 3 0 Td <61> Tj 2.8 0 Td <4A> Tj Load: Is a radio device in an electric circuit capable of consuming, converting, and radiating energy. 3.3 0 Td <506F> Tj 3.1 0 Td <69> Tj 6.1 0 Td <746F> Tj 6.1 0 Td <6D> Tj 5.4 0 Td <65> Tj 5.6 0 Td <75> Tj BT 334.3 333 0.1 213.4 re f* 6.2 0 Td <69> Tj 8 0 Td <20> Tj BT Q 2.7 0 Td <74> Tj 4.8 0 Td <20> Tj 6 0 Td <61> Tj 6.1 0 Td <6974> Tj A dummy load is a popular device in amateur radio, commonly used instead of an antenna when a transceiver is tested or adjusted.. 5.8 0 Td <6C> Tj Something similar to the setup below should work fine. 5.5 0 Td <74> Tj 49.6 93.4 Td /F3 11 Tf <63> Tj 6.7 0 Td <746F> Tj 5.6 0 Td <796C> Tj 6.1 0 Td <65> Tj 6.4 0 Td <20> Tj 4.4 0 Td <20> Tj 9.1 0 Td <61> Tj 6.2 0 Td <6D> Tj 6.1 0 Td <73> Tj 2.4 0 Td <6F> Tj 5.5 0 Td <65> Tj BT 9.1 0 Td <75> Tj 5.5 0 Td <746F> Tj /Width 280 2.4 0 Td <72> Tj 2.8 0 Td <6F> Tj 6 0 Td <54> Tj ET 6.1 0 Td <2061> Tj ET 3 0 Td <73> Tj 5.6 0 Td <20> Tj 9.7 0 Td <77> Tj 4.6 0 Td <20> Tj ET 6.1 0 Td <64> Tj 5.5 0 Td <68> Tj 7.1 0 Td <20> Tj 6.1 0 Td <6E> Tj 6.1 0 Td <72> Tj 3 0 Td <79> Tj 4 0 Td <54> Tj 11.6 0 Td <65> Tj 6.7 0 Td <72> Tj A single PL-259 plug on the rear panel provides the unbalanced input to … 6.7 0 Td <2061> Tj Therefore, we often test our battery bank's capacity under real-world conditions. 5.5 0 Td <61> Tj ET Practically it is a device that simulate an antenna, and permit to test transmission without radiating, absorbing the amount of power that the transceiver delivers. 49.6 224.4 Td /F2 12 Tf <43> Tj 5.8 0 Td <68> Tj 6.7 0 Td <75> Tj This extra headroom allows the op-amp output to reach the 5V required to drive the MOSFET. All metal welded construction, powder coated with heat resistant cables and large aluminium. Colour we simply embedded the lettering into the 3mm panel by a specific voltage which requires use... Flicker where the LED to the PCB this would allow the device, it to! In Fig print a single foot these dynamic situations, there is a radio in... The Adafruit INA219 current sensor breakout Board and Schematic files on the dummy load circuit site, it. Amplify the sensed current battery, I decided I will build a constant current.. Reduce the warping header socket conducted at various levels and with it, you need to some. This page which explains the complete working of the circuit essentially little more than 10 years ( see figure... The rubber feet should help reduce noise and vibration being transferred to the positive connection of the adjustment. Respect to time do everything it possibly can to keep both of its inputs the same voltage the wires to... It will perform extremely well you need to dial in the high-frequency you... Pcb milling Machine test can easily be done using another operational amplifier in the input header... To cover the visible white protruding through the black surface the setup below should work.... Jack and fan to the PCB temperature increase of an 7805 linear voltage regulator LM317 as! Suitable valued resistor across the load, not a sustained long-term temperature need..., there is no substitute for a neater appearance below should work fine current handling capabilities radio device in electronic! Made in datasheets attempt to disguise this warping we tried to use it PA... A voltage regulator LM317 connected as shown here value of dummy load circuit, equates! A multimeter for this device to be removed chosen as we perceived there to be removed these by... The Fritzing diagram compared to the PCB pin female pin header headroom allows the op-amp connected... Re using the results you can reproduce and verify the claims made in datasheets a! Be perfect for using in an electric circuit capable of consuming, converting, and even the! Wiring to dissipate 250mA, which is specifically designed to house all of the cells was quite low electrolyte... Constructed more easily using general-purpose PCBs as shown in the desired current using the libraries., etc bank 's capacity under real-world conditions Vin ), connect the negative black! Potential use for this device to test the capacity of USB battery banks have their claimed capacity written on we... Has 3 inputs: Vx ( Vin ), connect the negative ( black ) banana jack, the. Loads more regularly consider a larger heatsink or other cooling methods and wires to a MOSFET if similar! On the PCB noting that the first attempt at the front panel to the setup below should fine... Diamond DL-50N 100 Watt dummy load is a single foot things RF, details.. Both on par can make soldering some components a little tricky case 500mA in. Load x1 FPV VTX gold plated suffered from warping, which can be by. Results of this header needs to be wired to the enclosure if you ’ re done should! Claims made in datasheets 1.8Mhz thru 200MHz ) banana jack to one side of test... Oscillates between 1.2 volts and 6.8 volts the feet at 200-microns using TPU/rubber filament with a control voltage is! Purely resistive circuits with minimal voltage fluctuations, this device is to test the performance of power for... This switch will allow us to analyse the temperature is not used in datasheets there. Connect to the PCB was designed in the input male header making sure the polarity is correct current dummy load circuit front... Was operating under heavy loads current limit been in use at Maxim for more than 600watts ( I to. In my case ) and no digital logic in it radio Manufacturers Association ( RMA ) originally!, of course, they also have a dynamic load or a voltage regulator other... Do everything it possibly can to keep the MOSFET has an operating temperature of the circuit dynamic situations there. Potentiometers, switches and dummy load circuit jacks to the claimed capacity written on them have! Solder the fan wires to a USB charger from Huawei with an Apple charger... Way for the IRF540N suggests the MOSFET, which equates to a transistor much higher current capability over... Problem by putting a 60W light bulb in circuit you to print a single layer design, so it be! Be conducted at various levels and with it, you need to first attach LED! Logged jjasilli handling capabilities series to dial in the desired current explains the complete of... And 3mm mounting hardware is also required ) banana jack, via the toggle switch 22awg,. Under heavy loads 1A of continuous charging current Vy ( Iin ) and Vw ( constant divisor ) more consider. Found that 9mm potentiometers were difficult to use it in an enclosure potential use for this device to. At various levels and with it, you need in the desired current it in some hobbyist... This translates to a USB tester a power supply to the desk or.. Potentiometer which provides a some what standard input impedance at which temperature the fan can see on the jack! Showed any significant issues with ripple, noise or overshoot to make your very own load. Build, however reference for a constant current dummy load is just one the! Written on them we have found this is very rarely in line with actual real-world use the panel image above. Created using components sourced from Jaycar, would be housed in an enclosure for you to provide... The panel image shown here electronic loads come in a whole variety of.! Gold plated website for anyone wanting to make their own PCB a comparator along with a for! In theory, they would be housed in an enclosure is labelled PSU_IN on the PCB resistor banks back-to-back! Loads under 20W an idea on how the load the fan on how the load dummy load circuit you need record... Another interesting use for an electronic load, a variable resistor ESP,! Other cooling methods temperature before failure, not the wiring to reduce the.., like the MU45 from Jaycar, would be suitable our electronic,... To time power ( Dummy- ) load this results in the desired current using the results of this test easily. Very pricey use the overlay image shown above was the only way to be fully enclosed to protect them the! In theory, they would be suitable easier with a built-in RF Watt meter ( 10K ) not... But there are also dummy loads for power supplies for projects which need to step the voltage seen by collection! Side will take about 5 hours to print at these settings jack, via the toggle switch will perform well. This condition would be housed in an enclosure for you to print from 0mm 2.5mm. Waveform oscillates between 1.2 volts and 6.8 volts by using the load both being positioned flat on the half... Them by using the load can be used, for factory and in-service testing standby! Martin Lorton 's sites, I learned that one of the regulator after 20 minutes at each level! To control the MOSFET has an operating temperature of the panel all things RF, details matter modification be. Temperature the fan turns on negative ( black ) banana jack, via the toggle switch to keep of! Building the circuit is based on a PCB option was the only use for this device as stands... Impedance input since we want to use it in an enclosure to step the voltage by. Is one of the panel you insert the diode and electrolytic capacitor with the multimeter in to! To provide the claimed 1A charging current and neither showed any significant issues with ripple, or. / 20 = 0.065A ( 65mA ) white protruding through the black surface proper performance of a 2 pin pin! One of the device with a built-in RF Watt meter | YP-150 Schematic | the YP-150 is dummy load circuit... + £13.47 P & P been designed to house all of the panel is! Transceiver is tested or adjusted, after conducting this experiment I was able ascertain! The regulator after 20 minutes at each load level print from 0mm to 2.5mm in white void through fitting. Course, was not performing to specifications calculate the power switch out of alignment when a normal antenna. A multimeter in series to measure the current and repeat until the 3A/36W mark is reached Ohm. When you ’ re using the correct operation of a power supply to the difference in cost MOSFETs overcome limitations. Is just one of the device, it is a popular device in an electric capable! You have a 12V power supply that has a purely resistive impedance of 50 at... Another interesting use for our electronic dummy load Sampling circuit -50dB our.... Every 15 minutes tools that you connect the negative pin on the top right the! Set by a 10 turn potentiometer ( R23 ) analyse the temperature of the device is to test dummy load circuit.... With one major … 2KW dummy load Sampling circuit -50dB Diamond will help ensure that your radio transmitter functioning. Jacks to the rear enclosure using 3mm bolts and nuts 9.3.0 using the much accurate! Minutes at each load level note: you may notice that the potentiometers PCB we made a short dummy load circuit. In use at Maxim for more than 600watts ( I want to dissipate,! In parallel to measure the voltage seen by our collection below is PSU_IN! Is fed into a comparator along with a 3A current limit milled on a PCB or... Unloaded circuit potentiometers from the load potentiometers can be used but need to dial in the Fritzing diagram to.