Kerry Wong built a DIY constant current/constant power electronic load. It can sink more than 200W of power:
A while back I built a simple constant current electronic load using an aluminum HDD cooler case as the heatsink. While it was sufficient for a few amps’ load under low voltages, it could not handle load much higher than a few dozen watts at least not for a prolonged period of time. So this time around, I decided to build a much beefier electronic load so it could be used in more demanding situations.
One of the features a lot of commercial electronic loads has in common is the ability to sink constant power. Constant power would come in handy when measuring battery capacities (Wh) or testing power supplies for instance. To accommodate this, I decided to use an Arduino (ATmega328p) microcontroller.
Building a constant current/constant power electronic load - [Link]
Anthony H Smith writes:
The circuit in Figure 1 lets you switch high-voltage power to a grounded load with a low-voltage control signal. The circuit also functions as a submicrosecond circuit breaker that protects the power source against load faults. Power switches to the load when you apply a logic-level signal to the output control terminal. When the signal is lower than 0.7V, transistor Q3 is off and the gate of P-channel MOSFET Q4 pulls up to the positive supply through R6, thus holding Q4 off. During this off condition, the circuit’s quiescent-current drain is 0A.
Inexpensive power switch includes submicrosecond circuit breaker - [Link]
Debraj built an electrical dummy load to test his power supply:
Recently, I purchased a power supply that claimed a max current of 2A and 0~15V. So I wanted to test it. I had a 36 watts bulb (used in motor cycles), but that was too much. Then, I thought of the dummy load that is explained by Dave in his video blog. My version is similar, but I changed certain components to my liking (and what ever was already available with me)
Dummy electrical Load - [Link]
Vladimir Rentyuk writes:
Suppose that you need to test a 1.5V, AA-size alkaline battery. You can apply a short circuit and measure current, or you can measure open-circuit voltage, but neither method properly tests the battery. A suitable test current of approximately 250 mA gives you a more reasonable test. You can use a 6Ω resistive load at 1.5V, which produces an output voltage of 1.46V at an ambient temperature of 25°C if the battery is in excellent condition. A poor battery might produce less than 1.2V. Given the load, the output current at 1.2V will be 200 mA instead of 250 mA. The battery will have just 80% of a full load current. Instead, you can use the circuit in Figure 1 to produce a constant-current load.
Circuit provides constant-current load for testing batteries - [Link]
If you have an H-Bridge drive circuit for a motor, you may need a way to monitor the load on the circuit. This circuit is nice because it provides a single output that could be monitored with a microcontroller or other device. The trick is to use current sense amplifiers and measure the current on each leg of the circuit. The LTC6103 is a good choice because it has two sense amplifiers in the same package.
Here is a circuit diagram that will allow you to monitor the load.
Monitor your H-Bridge Circuit Load - [Link]
Paulo Oliveira writes:
An adjustable power load is a piece of test equipment that often comes handy in the development of a certain electronics projects. 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. Adding power resistors to the output can sometimes do in a pinch, but often you will not have the right resistor value handy with the right power rating for the test. This is where an adjustable electronic load comes handy. In this article, I’ll show how you can build one using common components available to the electronics hobbyist.
Building an Adjustable Constant Current Load - [Link]
Re:load is an adjustable constant current load with the following properties:
- No external power supply required – powered by the device under test
- Wide range of input voltages, from 3.3 volts to 32 volts
- Adjustable load from 0 to 3.5 amps
- Up to 14 watts power dissipation (with design heatsink)
- Virtually indestructable: The power FET, BTS117, has built in overtemp, ESD, and overcurrent protection
- Load remains constant under different input voltages – 40 milliamp variation over input voltage range
- Screw terminal and banana plug footprints
- Low BoM cost, and easy to solder thru-hole parts
- Test points for reading current with a voltmeter
A simple, flexible adjustable dummy load - [Link]
This is a simple constant current sink. It can be used to simulate a DC load. Need for it had arisen as I acquired a couple of cheap DC-DC converters and needed a way to test them, to see if they really put out the amount of current as advertised.
Some of the specs: 20V, 5A, 20W continuous dissipation, reverse polarity protection, 4mm banana-type binding posts for easy multimeter and load connection, current calibration with a 25-turn trimmer, 10-turn wire-wound potentiometer to set the current.
Simple DC Dummy Load - [Link]
The TPS22966 is a small, ultra-low RON, dual channel load switch with controlled turn on. The device contains two N-channel MOSFETs that can operate over an input voltage range of 0.8V to 5.5V and can support a maximum continuous current of 6A per channel. Each switch is independently controlled by an on/off input (ON1 and ON2), which is capable of interfacing directly with low-voltage control signals. In TPS22966, a 220-Ω on-chip load resistor is added for quick output discharge when switch is turned off.
TPS22966 – 6A Dual Load Switch with Controlled Turn On - [Link]
The design is based off of the EEVblog design shown on episode #102. The purpose of the device is for when you need a constant load to test things like power supplies, or batteries. No matter what the voltage coming out of the power supply, the constant current dummy load will adjust automatically to provide the same amount of current.
DIY Constant Current Dummy Load - [Link]