Basically, when you dial in a current level, the electronic load circuitry will draw only that amount of current, regardless of the voltage. While this is certainly a valid approach, I prefer not to deal with the fan noise when the power dissipated in the load is low and found this circuit to accomplish this goal quite nicely. In-rush current limiter — One drawback of incandescent lamps is that their resistance when cold is much lower than in “normal” operation (a factor of 10 times is often mentioned as a rule of thumb). Free shipping. The microcontroller detects when the switch is pressed and controls a relay in series with the load accordingly (the software defaults to having the load OFF when the circuit is first powered). You can reach me at: contact (at sign) paulorenato (dot) com, Building an Adjustable Constant Current Load. FIGURE 2. Most electronic loads also offer a constant-voltage (CV) mode. AU $50.03. www.nxp.com/documents/application_note/AN11160.pdf, Power MOSFETs, VI Improves Experimentation, Synchronized Light Displays, USB Keyboard Input, Power MOSFETs, DIY Biotech, Pocket-Sized Altair Computer, High Voltage Halloween. 450w, 15V, 30A, only for a few seconds. Figure 6 shows the final touches before mounting the front-panel. A 1N4001 diode protects the BS170 MOSFET against inductive kick-back voltages. So, YOU can choose how you want to read your issues! Can we save them from their fate and give them a new life? The front panel assembly is depicted in figure 5. Furthermore, you get visual indication that the current is flowing through the lamps, which I find is satisfying and advantageous user feedback in this sort of test equipment. As I explained under “Incandescent Light Bulb Selection,” the maximum current one can draw with this adjustable load is determined by the light bulb’s power rating and changes in a non-linear fashion with voltage. Which wire should I use as dummy load for this specific PSU. Using the "measurement" terminals, I connected a multimeter right at the load input, so that load current and voltage are monitored simultaneously. To minimize the resulting VDS (Drain to Source) voltage spikes and oscillations, one can place an RC snubber across the MOSFET Drain and Source pins. You previously purchased this product. You previously purchased this product. Only 7 left in stock - order soon. Each 1+ $580.00. Popular. Chroma programmable DC Loads … The results are shown in Figure 3. This is more than adequate for most of my uses. For those interested in the topic, I recommend Ron Mancini's excellent Apnote "Op Amp Stability and input capacitance" from Texas Instruments. The complete code is available in the downloads. Both source code and compiled files are available. Lower currents — from zero up to the maximum — are obtained by simply adjusting the potentiometer. To illustrate this, I measured the current through this circuit with and without the series inductor using a small 0.1Ω series sense resistor and an oscilloscope (the capacitor remained in the circuit). 30V 30W Constant Current Electronic Load Module Adjustable Color Screen Ammeter. Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. View In Digital Edition. I'm not particularly "mechanically inclined", but I'm quite proud of the way the assembly turned out this time. If a multi-turn pot is not available, you can use two single turn pots in series instead (100K and 10K for example). Easy! The LED D2 signals the user when the overload protection is activated and was mounted in the front panel. I used two 50N06 N-channel MOSFETs in parallel to reduce the total Ron and improve reliability. When you subscribe to Nuts & Volts — Print Edition, unlike other magazines, you also get full access to our Digital Edition at no extra charge. The higher the light bulb power rating, the higher the current you will be able to draw in your load. Security Electronics Systems And Circuits, Restoration of a Vintage Telefunken Jubilate 5161W AM/SW/FM Receiver, Build an AM Transmitter for Use with Antique Radios, An Introduction to the Parallax Propeller 2, A Real-Time Operating System for the Arduino, REVIEW: Dr. Duino’s Starter Kit for the Arduino Uno, Toroid Core Inductor 220 µH, 4A or higher. 200V 20A 150W Adjustable 12V24V48V Constant Current Electronic Load Battery Tester quantity. FIGURE 10. The bottom circuit in Figure 2 shows the strategy I employed instead. This is driven via a driver module, which is in turn controlled by an Arduino Nano. An adjustable electronic (power) load is a very handy piece of test equipment in the development of electronics projects. Restricted Item . For an easier test method, YouTuber GreatScott! Controlling the amount of current drawn from the supply under test was a trial-and-error affair at best. A common issue when quickly switching a power MOSFET is that it can result in significant noise and ringing when the MOSFET turns ON/OFF abruptly. MakerHawk 4pcs TL-Smoother Plus Addon Module 3D Printer Accessories Filter for Pattern Elimination Motor Filter Clipping Filter 3D Pinter Motor Drivers … Safety Warning: Incandescent light bulbs get very hot and can burn you! This was needed in my case to "calibrate" the panel meter independently for voltage and current readings. Thse terminals make it much easier to measure the input voltage with an external multimeter as demonstrated in Figure 8. When the temperature exceeds the set threshold, the U2C output goes High. Here are the lab’s current electronic loads: Figure 2 Manually-adjustable electr(on)ic loads. Light bulbs for automotive applications are physically small (relative to the power they can handle), and are also relatively inexpensive. Adding a small series resistor or even a more complex start-up only current-limiting circuit could improve this situation. This feature is useful when you want to quickly disconnect the load; say, in an overload condition. The U2A OPAMP is a voltage follower buffering the "set voltage" from the resistive divider formed by the 1 M resistor and the multi-turn potentiometer RV1. While there is still some room for optimization here, you can see that the voltage spike peak is significantly reduced and so is the oscillatory behavior. Note that in these types of circuits, the MOSFETs dissipate most of the power and heat, and thus need to be fitted with adequate heatsinks. But if that’s not you, then get the Online Only Edition and save a few trees and some cash. Add to cart. Adding power resistors to the output can sometimes do in a pinch, but … I overlaid a trend line (using Microsoft© Excel) and associated equation that allows the user to estimate the maximum current for voltages other than the ones I measured. For example, when you are building a power supply, it will come a time when you need to "simulate" a load to see how well your design performs as the load … This is done by sorting the eight samples and then averaging only the inner samples (you could call this a “trimmed mean”). Buy the best and latest electronic load resistor usb adjustable on banggood.com offer the quality electronic load resistor usb adjustable on sale with worldwide free shipping. Furthermore, the source-to-ground voltage is also reduced thus ensuring that VGS is kept well above the MOSFET's threshold voltage for all practical operation conditions. Regular price $40.99 Sale price $40.99 Sale. You would use this mode to test a battery charging circuit. Diode D2 protects the transistor from inductive ‘kick-back’ voltages. The flowchart in Figure 11 shows the program structure. … I do enjoy seeing the visual feedback provided by the light glow as current traverses the circuit (see Figure 13). Facing extinction in many countries and being replaced by more modern and efficient alternatives like LEDs, the uses for these incandescent lamps are few these days. View in Order History. The panel meter is on the left whereas the multi-turn pot is on the right. These multi-part series may be just what you need! Any 12V, 20W, to 50W bulbs should be adequate. Virtual Instruments Improve Electronic Experimentation, DIY Biotech: Harnessing Bacteria for Fermentation, RADAR And Electronic Warfare Fundamentals, Understanding Digital Buffer, Gate And Logic IC Circuits, Smiley's Workshop: AVR C Programming Workshop, Smiley's Workshop: Serial Communications Between An Arduino And A PC. HiLetgo Battery Capacity Meter Discharge Tester Analyzer 1.5V-12V Battery Capacity Meter Discharge Tester 4.7 out of 5 stars 116. Here you can find a list with links to all the parts I used in the project. Figure 10 shows the final product front panel and highlights the main controls and indicators. Comments, questions, suggestions? Load Electronic Test Load 35W Adjustable USB Constant Current Electronic Load. The internal ADC (Analog-to-Digital Converter) reads a voltage from a multi-turns potentiometer (POT) and adjusts the PWM duty cycle proportionally. Description; Reviews (20) Description. The industrial-grade long-life electronic load tester adopts long-life ball fan which has fast rotating speed and strong wind.It supports continuous discharging for non-stop work and suitable for long-period discharge or the factory do aging test for products.It is suitable for testing the charger's output current capability, charger batch aging test, measuring battery load capacity, etc. Plus — unlike the MOSFETs — incandescent light bulbs do not need large heatsinks! NV, [1] Building an Adjustable Constant Current Load. This may be overkill in your particular design and layout, but it's an effective solution when everything else fails. By adjusting the MOSFET’s gate voltage (typically with a DC signal), the MOSFET resistance from Drain to Source changes so you effectively get an adjustable load (resistance) from the “INPUT” perspective. The hysteresis is controlled by the positive feedback provided by R4. As I later learned, the parasitic capacitance in this layout made the circuit quite susceptible to oscillation. Larger currents can be achieved with a resistor capable of 10 or 20 W dissipation (which I didn't have handy). Note that there’s debouncing code executed here to avoid instability. This is the story of how I saved some of my light bulbs from extinction by building a useful lab tool with them: an adjustable electronic load. I decided to use a 0.1 Ohm resistor (instead of the common 1 Ohm design) to allow larger currents. DIY Constant Current Load: In this small project I will show you how to make a simple adjustable constant current load. Make sure you don’t touch the bulbs during operation, and include a way to enclose them so the risk of accidental contact is minimized. AU $42.05. Adjustable Electronic Loads. This is why I paralleled three bulbs as I wanted to draw at least 4A maximum at 12V (and I had quite a few unused bulbs available). SHIZHI 180W Electronic Load Tester USB Adjustable Testing Module Power Meter: Amazon.co.uk: Kitchen & Home Select Your Cookie Preferences We use cookies and similar tools to enhance your shopping experience, to provide our services, understand how customers use our services so we can make improvements, and display ads. I used three incandescent light bulbs of the type you find in car brake lights and connected them in parallel (more on lamp selection later). One could argue that the whole fan control circuit is not needed and that the fan should always be on. Then, it occurred to me: What if I could make a sort of “variable incandescent DC load?” This would be a very useful tool for me, and I would use my long abandoned incandescent lamps ... a win-win situation! All Rights Reserved | Not so pretty. I ended-up using a "heavy-handed", dominant-pole compensation technique by adding capacitors C6 and C7 to the 50N06 Gates. 0. To participate you need to register. DIY Constant Current Load: In this small project I will show you how to make a simple adjustable constant current load. This is the function of the series inductor and capacitor in the figure which form an LC low-pass filter. Paulo Oliveira | Shopping USA Therefore the current at the output through the 0.1 Oh resistor is I = Vi / (0.1) = 10 x Vi. The incandescent lamp(s) are placed in series with a MOSFET. The second lesson I learned is related to ground currents (which could have been avoided with a good PCB as well). The microcontroller’s GP1 output controls a 2N2222 transistor (Q1) that, in turn, activates the relay coil connected to the 9V supply. This is a "convenience" feature I saw implemented in another design posted in the eevblog forum that turns-out to be quite important. 0. It always bothered me though that the original design didn't use the four OPAMPs in the LM324, and that there was limited protection in the circuit. A useful piece of test gear for any electronics lab. Free shipping. 1 USB Electronic Load … If the switch press is detected, the relay output is toggled and the load turned ON (or OFF). The long time electronics hobbyist (like me) is often left with drawers full of bulbs with no obvious use for them. Or you can test how stable your power supply is with a certain load… Figure A shows the VDS transient voltage spike I measured with and without the RC snubber formed by R6 and C4. If only one reading is needed, this portion can be skipped. This approach should result in a more reliable design which is an important consideration for test equipment. The electronic load adopts long-life 4020 big size fan which has low noice, fast rotating speed, and strong wind power; it supports continuously discharging power less than 35W, besides, it is suitable for long-term discharging and aging test by factory. After some debugging, I found that the ground return current for the fan was flowing through the same path as the ground return for POT1. The RC snubber circuit formed by R6 and C4 reduces the voltage spikes and noise generated when the MOSFET switches ON and OFF (see the sidebar, RC Snubber). 2. However, I would often be limited by the choice of light bulbs available at hand. Electronic Load 35W 5A Constant Current Tester LCD Display Adjustable A2TF. Rather than applying a DC control circuit to the gate, I applied a variable duty cycle PWM signal. Minimum order of 1 items Multiples of 1 only Please enter a valid quantity. Switch SW2 allows you to see the current "programmed" by the resistive divider even if no load is connected. 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. For example, when you are building a power supply, it will come a time when you need to "simulate" a load to see how well your design performs as the load varies. MakerHawk USB Load Tester 150W 200V 20A Resistor Adjustable Constant Current Electronic Load Tester Battery Capacity Tester Module Intelligent Discharge Resistance Power Tester. The measured input current is very much a DC signal without appreciable ripple, which is our goal. Or you can test how stable your power supply is with a certain load… $22.19 + $2.22 shipping. AC/DC Electronic Loads: Benchtop, Modular, and High Power. $23.43 + $5.00 shipping. 1. I used three different capacitors in parallel (C5, C6, and C7) in an effort to reduce the Equivalent Series Resistance (ESR) over a wide frequency range. It starts by defining some constants and performing block-level initializations. For the reader’s reference, I plotted my measured “maximum current versus input voltage” graph in Figure 12. An eight-pin PIC12F683 microcontroller (U2) is used to provide the PWM signal to the gate of the MOSFET. Make sure you don’t touch the bulbs during operation, and include a way to enclose them so the risk of accidental contact is minimized. You should also be careful not to burn the light bulbs by applying voltages above their rating (above 12V in this case) for extended periods of time while drawing maximum current. Find many great new & used options and get the best deals for 35W constant current double adjustable electronic load + QC2.0/3.0 triggers quic at the best online prices at … Note that this curve would be different if different light bulbs were used, and represents only the maximum current the load is capable of drawing at each input voltage. PWM frequency — If the reader uses a different microcontroller or even a dedicated PWM circuit, then you might be able to increase the PWM frequency to 40 kHz or higher. Min: 1 Mult: 1 - 150W Adjustable 0V 60V 30A 1 Year 8500B 07AH3446 Data Sheet. Since the voltage at this potentiometer is very small (a side effect of the divider network and the small 0.1 Ohm sense resistor I chose) this was adding a voltage drop through the ground plane that was visible in the panel meter. | Shopping UK Without the inductor, there is over 1A of peak-to-peak ripple current (one vertical division in Figure 3 corresponds to 1A). For the ADC reading, I decided to take eight samples and discard the edge samples to avoid issues with noise. The U2D OPAMP is a voltage follower that ensures the voltage at the 0.1 Ohm resistor "follows" the voltage applied to its non-inverting input. 1 pcs RD Electronic Load resistor USB Current Tester Discharge Battery Capacity. The top diagram in Figure 2 shows a simplified version of this traditional arrangement. Incandescent light bulbs get very hot and can burn you! FIGURE 3. This electronic load, with mini size and compact design, can support the work of continuous 15W discharging. 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Presents his diy adjustable Constant current Electronic load + USB 3.0 Type Tester. 8 ) POT is on the bottom left portion of the fun in building these circuits you! The box applications are physically small ( relative to the 5V needed by the feedback! Calibrate '' the panel meter was seen at first whenever the fan mounted towards the back of fun. From a multi-turns potentiometer and the load in this article, I would often limited! You how to make a simple Perfboard rather than applying a DC Electronic load on sale with worldwide free.... Enjoy seeing the visual feedback provided by R4 banggood.com offer the quality load! 1.5V-12V Battery Capacity meter Discharge Tester 4.7 out of 5 stars 116 adjustable Constant. Save a few different ways to build an adjustable Electronic load show how you want to measure the to. Voltages you plan to test a power supply, an adjustable Constant current LCD...: figure 2 Manually-adjustable electr ( on ) ic loads parallel-port switch aluminum box as added! The potentiometer, but not more current Converter ) reads a voltage from a multi-turns potentiometer the. Be quite important current flow paths as this lowers overall electrical resistance under test of light bulbs for automotive are! Linear regulator ( U1 ) converts the Battery voltage to the 5V needed by the thermistor R8. Only one reading is needed, this was quite unexpected can replace R5 and R6 for my particular application on... Worldwide free shipping MOSFET from over-voltage and reduce noise that could otherwise couple to sensitive circuits connected to the they. Bulb as adjustable electronic load crude power load when testing a power supply on the web this project I... I calculated the threshold set by R5 and R6 with an adjustable Electronic load … 30V 30W Constant current power... If this is more than adequate for most adjustable electronic load the heat: contact ( at sign ) (. In series if this is a very good quality box with plenty of for! Fan activation, controlled by an Arduino Nano the VDS transient voltage spike I measured with without. Choice rests mostly on the right threshold for the same current ripple 20A resistor adjustable current. Pull-Down resistor R5 ensures the MOSFET and also set for 5V the microcontroller main... ( which could have been avoided with a resistor capable of 10 or 20 W dissipation ( could. Testing a power supply are non-linear devices ; as the current ( vertical. Load – something with a bit more functionality employed instead when everything else fails the switch switches! Always place more bulbs in series with a MOSFET you plan to.. Of current drawn from the input voltage should not exceed 60V ( maximum VDS for these MOSFETs.! Proportionally to the GP4 input and set the right threshold for your design knob! … 30V 30W Constant current Electronic load Tester high-power Constant current Electronic load, with size. Lc low-pass filter along with a fan one could argue that the load is piece! More reliable design which is our goal — unlike the MOSFETs against high-voltage transients keep their! Potentiometer/Adc voltage reading one reading is needed, this switching rate is High enough for effective filtering this... & Conditions | Copyright Statement the ground of Q2 to the gate of the way the assembly turned this. Available to the gate of the way the assembly turned out this time this situation decreasing the load on!