For a power hungry project the supply is sometimes a pretty big unknown. Whether stapling together a few different power supplies to meet a current requirement, or designing a system from the ground up: a big power supply can be quite a dangerous thing. It helps to have some kind of a dummy load to really shake down the electronics and get an idea of how hot things get or test stability before trusting the supply to run your stuff. [Paulo Oliveira] has constructed just such a thing, a slick looking adjustable constant current load.
Following the popular LM324 circuit from [David Jones] at EEVblog [Paulo] decided to make use of the two spare op-amps to provide both a thermal overload and a cooling fan circuit. We have seen other tweaks to [David]‘s circuit in the past but through some resistors and MOSFETs [Paulo] can now load up to 7A (limited by resistor wattage). We would have used a really crazy server
vacuum fan to make it genuinely frightening to push heavier loads. Thanks [Paulo]!
by Jesse Congdon
Filed under: how-to