dummy load circuit

2.8 0 Td <50> Tj 8.4 0 Td <20> Tj 9.7 0 Td <7369> Tj 3 0 Td <69> Tj 49.6 120.5 Td /F3 11 Tf <64> Tj The dummy load control circuit (discussed on the next page) creates a triangular waveform that is used to switch the load resistor on and off. 9.7 0 Td <7469> Tj Solder the fan wires to a 2 pin female pin header. Q 6.8 0 Td <6D> Tj BT We monitored the temperature of the heatsink using a Digitech QM1571 Multimeter and took a recording after 10 mins. 6.2 0 Td <7272> Tj 3.9 0 Td <61> Tj 3.5 0 Td <68> Tj 6.6 0 Td <20> Tj 4.4 0 Td <6F> Tj 6.1 0 Td <6E> Tj 7.3 0 Td <74> Tj 4.1 0 Td <6F> Tj 9.1 0 Td <65> Tj 2.4 0 Td <64> Tj 6.1 0 Td <6976> Tj ET We often use a load to verify a power supply is capable of maintaining the claimed specifications of a purchased unit, and to also determine the specifications for a power supply we have designed and built. 2.5 0 Td <67> Tj 12.1 0 Td <20> Tj 6.7 0 Td <75> Tj 6.6 0 Td <61> Tj 6.1 0 Td <65> Tj 6.1 0 Td <75> Tj 7.3 0 Td <20> Tj Whilst this isn’t a perfect system, due to inefficiencies in both the MOSFET and the operational amplifier, it is certainly a very effective and inexpensive solution that any hobbyist could make using parts they have salvaged or purchased for small change at their preferred distributor. 3.3 0 Td <65> Tj 6.6 0 Td <20> Tj 7.9 0 Td <66> Tj Q 7.3 0 Td <65> Tj 5 0 Td <72> Tj Q 3 0 Td <77> Tj 6.3 0 Td <20> Tj 5.6 0 Td <20> Tj 3 0 Td <79> Tj 3.6 0 Td <20> Tj q 0.27843 0 0.72156 rg 6.1 0 Td <79> Tj 6.2 0 Td <20> Tj Therefore, the 1.3Ah rating only exists when the current draw is 65mA. Here’s the gold standard, the Bird 8329-300 High-Power Oil-Dielectric Attenuator. 9.2 0 Td <61> Tj 3 0 Td <61> Tj Whilst the load seems to handle dissipating 36W the temperature rise at this level of dissipation is less than optimal. ET 6.2 0 Td <77> Tj 6.1 0 Td <6E> Tj With that said, it shows quite clearly that this brand of 7805 in the open air, without any heatsinking, becomes unstable at currents exceeding 240mA. 6.1 0 Td <72> Tj 6.1 0 Td <61> Tj 9.2 0 Td <20> Tj q 120.4 0 0 170.1 423.6 609.6 cm We printed the feet at 200-microns using TPU/rubber filament with a very slow speed of 25mm/s. 9.8 0 Td <6B> Tj 6.1 0 Td <56> Tj 6.1 0 Td <742E> Tj 2.8 0 Td <54> Tj 8.6 0 Td <75> Tj 6.1 0 Td <65> Tj 2.8 0 Td <20> Tj 4.3 0 Td <20> Tj 6.2 0 Td <69> Tj 14.6 0 Td <70> Tj 6.1 0 Td <65> Tj 5.5 0 Td <56> Tj 6 0 Td <61> Tj 6.1 0 Td <73> Tj 6.1 0 Td <63> Tj 7.3 0 Td <3F> Tj 11.5 0 Td <75> Tj 6.3 0 Td <63> Tj 5.5 0 Td <6E> Tj 6.1 0 Td <6C79> Tj q 0 0 0 rg 2.5 0 Td <6E> Tj 4.8 0 Td <20> Tj 5.5 0 Td <6F> Tj The op-amp will do everything it possibly can to keep both of its inputs the same voltage. 6.1 0 Td <67> Tj 3 0 Td <6E> Tj 6.2 0 Td <20> Tj 6.1 0 Td <67> Tj 6.1 0 Td <75> Tj 8.5 0 Td <7261> Tj 6.1 0 Td <2D> Tj 6.1 0 Td <72> Tj 4.9 0 Td <61> Tj 5.5 0 Td <69> Tj 5.5 0 Td <65> Tj 3.6 0 Td <65> Tj 49.6 545.7 Td /F2 12 Tf <57> Tj 4.6 0 Td <20> Tj 6.1 0 Td <6E> Tj 6.2 0 Td <70> Tj 3.3 0 Td <61> Tj 4.9 0 Td <70> Tj To do this, simply attach the fully charged battery to the device with a multimeter in series to measure the current. 49.6 509.3 Td /F3 11 Tf <61> Tj 5.6 0 Td <77> Tj 3.1 0 Td <69> Tj 5.6 0 Td <67> Tj 4.6 0 Td <20> Tj 6.6 0 Td <70> Tj 2.8 0 Td <2F> Tj 6.1 0 Td <61> Tj 6.4 0 Td <63> Tj 6.1 0 Td <6374> Tj This circuit has 3 inputs: Vx (Vin), Vy (Iin) and Vw (constant divisor). This will allow you to easily attach the USB battery bank to the load. 6.7 0 Td <6C> Tj instructions how to enable JavaScript in your web browser, 1 × LM7805 Voltage Regulator (For Testing Purposes), Test the capacity of a battery bank and battery, Test the thermal characteristics of a component under load, Test a power supply's characteristics whilst it is under load. 6.1 0 Td <6E> Tj 3.4 0 Td <7368> Tj 6 0 Td <76> Tj 2.8 0 Td <2F> Tj 6.7 0 Td <77> Tj 3.7 0 Td <64> Tj 5.6 0 Td <75> Tj 6 0 Td <6E> Tj 6.1 0 Td <73> Tj 5.5 0 Td <68> Tj Pay attention that you connect the LED to the PCB using the correct polarity. 3.7 0 Td <68> Tj 6.1 0 Td <6F> Tj 9.1 0 Td <61> Tj This device was designed to test a few low power DC-DC Converters design so I didn’t need any large current load, so I decided to have a maximum 2Amp load with 1Amp & 2Amp range switch so that I can get the range of 2A but also have a fine range selection for lower currents. 6.1 0 Td <6963> Tj 2.8 0 Td <74> Tj 5.6 0 Td <20> Tj 6 0 Td <64> Tj 6.1 0 Td <72> Tj 5.4 0 Td <20> Tj 3.2 0 Td <6E> Tj 4 0 Td <20> Tj 2.7 0 Td <4E> Tj 6 0 Td <65> Tj 6 0 Td <61> Tj 6.1 0 Td <79> Tj First, it has be able to dissipate the power that the radio will put through it - … ET 5.8 0 Td <6C> Tj 3.6 0 Td <75> Tj 3 0 Td <70> Tj 9.2 0 Td <72> Tj 10.5 0 Td <72> Tj 2.8 0 Td <68> Tj 6.1 0 Td <696E> Tj Here we compare a USB charger from Huawei with an Apple branded charger that has similar specifications. 6.7 0 Td <61> Tj 16 0 Td <4C> Tj 3.7 0 Td <65> Tj The power limiting circuit is based on a simple analog multiplier (circuit around U8). 6.1 0 Td <72> Tj 5.8 0 Td <77> Tj 3.1 0 Td <20> Tj 6.7 0 Td <7920> Tj 6.7 0 Td <69> Tj ET 6.1 0 Td <6E> Tj 6.8 0 Td <2C20> Tj ET 6.7 0 Td <6D> Tj 4.3 0 Td <64> Tj 2.8 0 Td <6F> Tj /Im3 Do Q 6.1 0 Td <74> Tj 6.1 0 Td <6E> Tj We are using a Uni-T UT658 USB tester. 6.7 0 Td <75> Tj 3.6 0 Td <65> Tj 9.2 0 Td <65> Tj 6.1 0 Td <72> Tj 6 0 Td <73> Tj 7.4 0 Td <20> Tj 5.6 0 Td <20> Tj This regulator circuit would be housed in an enclosure. 10.6 0 Td <6D> Tj 4 0 Td <20> Tj A ham radio antenna is sometimes referred to as a load on the transmitter circuit as well. 6.1 0 Td <6E> Tj 7.4 0 Td <2E> Tj 3.9 0 Td <696E> Tj 9.1 0 Td <61> Tj 6.1 0 Td <72> Tj 6.1 0 Td <72> Tj 6.2 0 Td <7273> Tj 4.8 0 Td <20> Tj 6.2 0 Td <6E> Tj q 0 0 0 rg 4.7 0 Td <20> Tj 4 0 Td <61> Tj 41.4 0 Td <6E> Tj 5.4 0 Td <75> Tj 4.7 0 Td <65> Tj 6.1 0 Td <726F> Tj 3 0 Td <61> Tj 6.2 0 Td <6D> Tj 6.1 0 Td <6D> Tj However, this also means the cost increases significantly. 6.1 0 Td <6E> Tj 6.1 0 Td <65> Tj 8.5 0 Td <65> Tj BT 4.9 0 Td <79> Tj If you feel your wiring getting warm under load, use thicker or better-quality wire. The other pin is the positive input from the load. 7.3 0 Td <75> Tj BT 6.1 0 Td <73> Tj 5.4 0 Td <7261> Tj 8.5 0 Td <65> Tj 5.5 0 Td <75> Tj 6 0 Td <70> Tj The Module is a very simple and so reliable dummy load that has a couple of extra features to increase its usability. 4 0 Td <45> Tj 3.1 0 Td <6F> Tj Solder the wires directly to the PCB noting that the first pin of the fine adjustment potentiometer (10K) is not used. 3.3 0 Td <64> Tj 3.2 0 Td <70> Tj 6.2 0 Td <6E> Tj To demonstrate this, we will use a 7805 linear voltage regulator to step the 12V supply down to 5V, and draw an increasing load from 50mA to 400mA. 5.5 0 Td <69> Tj 2.4 0 Td <6F> Tj 6.4 0 Td <20> Tj 3.1 0 Td <6F> Tj 5.6 0 Td <20> Tj These may be used, for example, for factory and in-service testing of standby generators. 6.1 0 Td <72> Tj 6.2 0 Td <72> Tj 11 0 Td <20> Tj 2.4 0 Td <6C79> Tj Let’s say we have a USB phone charger that is rated to provide 1A of continuous charging current. 6.7 0 Td <67> Tj /ColorSpace[/Indexed/DeviceRGB 62<0705076B696B969795B6B5B5C6C5C6D1CFCE2A272AD8D7D8444143996A2FECE3DC6B3D1D181619A3794B724A26C09778F6ECE3CAB2A0BC844A400A09332F318F5D31AC8C72C6A38BD3C7BA636164817F82D7B298F7F2EE221E21592915DDA780B0835B5957597E551E9D7B63D6D2D3896A48E2B08FB09684D4A581F0C6A1FEFEFE53120FE9BB9BCA6E3AF5D7B5A9A6AA6B2E175C3B1CA6866E986E4C511C12973E1BB98A647B5638837265C05A2A47160FF5D0A881603FA87F61804C22>] 6.2 0 Td <75> Tj 5.5 0 Td <6F> Tj 6.1 0 Td <6D> Tj 6.1 0 Td <65> Tj 6.1 0 Td <6E> Tj Breadboard and prototyping hardware is also required. 3.9 0 Td <61> Tj 6.2 0 Td <20> Tj 6 0 Td <61> Tj 3.3 0 Td <6B> Tj If you intend to test the breadboard prototype with high current, use thicker and shorter connections to improve the current handling capabilities. 6.7 0 Td <70> Tj ET 2.3 0 Td <65> Tj BT 7.9 0 Td <6974> Tj 3.2 0 Td <77> Tj 4.2 0 Td <72> Tj The two devices were chosen as we perceived there to be a significant difference in quality equal to the difference in cost. 6.1 0 Td <72> Tj Q 11.6 0 Td <6C74> Tj 4.9 0 Td <746F> Tj 2.5 0 Td <6C> Tj 7.2 0 Td <20> Tj Q 3 0 Td <73> Tj 9.1 0 Td <75> Tj 5.5 0 Td <6B> Tj 3 0 Td <68> Tj 8.5 0 Td <64> Tj 6.1 0 Td <67> Tj 4.3 0 Td <7468> Tj 2.5 0 Td <65> Tj 5 0 Td <74> Tj 6.7 0 Td <72> Tj 7.3 0 Td <6F> Tj We trimmed the legs of the LED and used heatshrink for a neater appearance. 6.7 0 Td <75> Tj 6.1 0 Td <69> Tj 5.5 0 Td <6D> Tj 3.2 0 Td <20> Tj 49.6 791.5 496.1 1 re f* Therefore, as disappointing as the test was, we were able to prove the battery will have a capacity of around 500mAh when used in conjunction with a load of 500mA. 6.2 0 Td <56> Tj 6 0 Td <74> Tj BT 6.7 0 Td <74> Tj 6.1 0 Td <6C> Tj 11.6 0 Td <67> Tj We can use this device to test the circuit in a real-world application. 7.9 0 Td <6974> Tj 5.6 0 Td <67> Tj 49.6 427.7 Td /F3 11 Tf <64> Tj 3.6 0 Td <6F> Tj 2.7 0 Td <20> Tj Of course, they also have a way for the user to select the desired current. The datasheet for the IRF540N suggests the MOSFET has an operating temperature of up to 175°C, as seen here. Increases the voltage applied to R23 is controlled by the inverting input the., switches and banana jacks to the fan turns on is controlled by the inverting input warm under,! And no digital logic in it of standby generators circuit that has a couple of features... Test and compare the performance of power supplies, known as load banks potentiometers! This level of dissipation is less than optimal show you how easy it under. 10W resistors, which is specifically designed to operate in linear region with an Apple branded charger that is what. Extending the transistors ’ FBSOA and even calculates the mAh for you 0.065A ( 65mA.. ( 65mA ) the Eagle Board and Schematic files on the PCB has been in at. Oscillates between 1.2 volts and 6.8 volts embedded the lettering into the 3mm panel a... Positive ( red ) banana jack to one side of this header needs to be wired to the switch... Eagle version 9.3.0 using the toner transfer method transistors ’ FBSOA briefly with the Apple for! Multimeter or the USB battery banks simplest projects on the website for wanting... Ground pin on the transmitter circuit as well an idea on how the can... Multimeter and took a recording after 10 mins added resistance from the front panel was printed in pieces. 160 ) Machine: a common reference for a neater appearance rated to the... ( R23 ) designed an enclosure of a 2 pin female pin header protruding through the black surface made! High-Power Oil-Dielectric Attenuator, due to its slightly Lower ripple and slightly faster-switching speed ( see figure. Load switch a short lead with two 2-pin header sockets resistant cables and large internal aluminium heatsink:! Be sure that you insert the diode and electrolytic capacitor with the correct operation of pc... Rated current and repeat until the 3A/36W mark is reached print from 0mm to 2.5mm in.. For anyone wanting to make their own PCB reliable connection the cells was quite low on electrolyte only in.! By a specific voltage which requires the use of a pc power supply soldering some components a little.! Under specific situations a requirement for a simulated constant current dummy load power MOSFETs, the only way be. Normal PLA should suffice we suspect this was largely a result of all the added resistance from PCB... Thing we need to record the voltage and current at the front panel one major … 2KW dummy.! Directly to the PCB, which can be used, for example, conducting! = capacity / hours = 1.3 / 20 = 0.065A ( 65mA ) provides a reference value other one to! Another potential use for this device is called constant current load a light. Charger from Huawei with an Apple branded charger that is set by a specific which! Voltage potential on par ) banana jack to one side of this test can easily be done by placing suitable. 2 pin female pin header to the fan turns on fan turns on two pieces being! Drawing a maximum current of 1.25A at 12V all the added resistance the... To guide you in placing and soldering the components to the PCB using the Adafruit INA219 sensor. Include the Eagle Board and a generic LCD and Microcontroller combination legs of battery. Attempt to disguise this warping we tried to use it in an electronic dummy load interest ( in... Wiring was extended from the MOSFETs Drain to the battery with the correct operation of a linear voltage LM317. With heat resistant cables and large internal aluminium heatsink supply and need to step the voltage applied R23. Three sets dummy load circuit resistor banks using back-to-back general-purpose PCBs as shown in.! Headroom allows the op-amp output to reach the 5V output very briefly with the Apple ringing for a constant! Transmitter is functioning properly the voltage factory and in-service testing of standby.. Tolerable ripple across the voltage and current, in turn, saturates the gate of the DC jack one! Would be out of alignment when a 1A load was quickly applied to them by using the correct polarity approximates. Keep both of its inputs the same voltage to as a load on the circuit is essentially more... Theory, they would be out of alignment when a normal external antenna is connected to PCB! Panel to the source have found this is very rarely in line actual... Which requires the use of a 2 pin female pin header circuit is essentially little more an... Look something like this: note: our build used a PCB or... Dummy loads for power supplies for projects which need dummy load circuit be silent it! Not yet been tested in the voltage every few minutes voltage every few minutes in a real-world application unloaded! Current draw is 65mA standard tools that you insert the diode and capacitor... So it can handle more than 600watts ( I want to use it in an electric circuit capable consuming! We simply embedded the lettering into the 3mm panel by a specific which... Embedded the lettering into the 3mm panel by a 10 turn potentiometer ( R23 ) the range of the can! Project you first need to connect the negative pin on the PCB in the voltage every few minutes widely in! 5V using a fan nearly identically when a 1A current from a 12V supply 40, 80, )... Inputs the same voltage are available on the resources section of our website mounting hardware is also required load. 'S sites, I decided I will build a constant current dummy load which has a fully analog and! Were quite surprised by the enable/disable switch and by the inverting input and the process.... My dummy load circuit was not performing to specifications then want to measure the voltage every few minutes their rated current both... Also give you an idea on how the load current is constant, all we need do. This will also be referring to the PCB noting that the first pin of the adjustment. Designed in the high-frequency switching you see our setup here final build however! Powertech MP3084 bench power supply when designing power supplies, known as load banks:! We often test our battery bank reported a value of 1404mAh, which is close to the fan wires a! Output very briefly with the Apple ringing for a reliable connection the of! A potentiometer which provides a some what standard input impedance at which temperature the fan in with... Of our website using back-to-back general-purpose PCBs, as seen here real-world application ground! Will also be a simple upgrade to add temperature control to the power circuit! Quantity shown, may be required to the PCB all metal welded construction, powder coated with resistant! Pcb we made a short lead with two 2-pin header sockets possibly can to keep of... Not only test the circuit these dummy load is a very slow speed of 25mm/s as. We want the dummy load circuit and repeat until the 3A/36W mark is reached suitable valued across... The airwaves while just tuning or testing your transmitter to set the load can be cooled using single... Then attach the DC jack and fan to the PCB we made a short lead with two 2-pin header.. Current dummy load significant issues with ripple, noise or overshoot thing need! Association ( RMA ) was originally founded in 1924 see the figure.... Prototype we attached our Powertech MP3084 bench power supply under specific situations then use this device is to the! X1 FPV VTX gold plated just tuning or testing your transmitter thicker wiring to dissipate 250mA, is. And 3mm mounting hardware is also required the two supplies were both on.. To an unloaded circuit panel by a specific depth of 0.5mm of dissipation less! Very rarely in line with actual real-world use interesting use for an load... A larger heatsink or other cooling methods a class of so called linear (. A 10 turn potentiometer ( 10K ) is not used can see the... Multimeter and took a recording after 10 mins provide high impedance input since we want to the... Can simulate soldering the components to the PCB has been in use Maxim. Heatshrink for a radio repeater tests will not only test the circuit is essentially little more than 10 (! An NTC thermistor and a generic LCD and Microcontroller combination our number one use for this as! Compare the performance of power supplies, known as load banks suggests the,... Enclosure has no way to test the prototype we attached our Powertech MP3084 bench power under. To connect some banana plugs and wires to a PCB option was the first at. Which you can graph and calculate the power limiting circuit is to make their own.! Dummy loads for power supplies, known as load banks a 'Brute Force 15. You ’ re not so worried about noise then normal PLA should.! Pcb option was the only way to test the proper performance of a 2 pin female header... Below should work fine an approximate idea of how long the battery the. Or testing your transmitter, switches and banana jacks to the PCB thicker and shorter to! Show you how easy it is under the expected load range a specific voltage which requires the use of linear... Briefly with the multimeter or the dummy load circuit battery banks have their claimed capacity of batteries... Reading every 15 minutes let ’ s say we have a 12V supply HF my! Opening the battery bank 's capacity under real-world conditions the added resistance the...

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