Test your project’s mettle with a protected dummy load

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]!

Comments

  1. Chris C. says:

    I always appreciate a project that includes a detailed “Lessons Learned”.

  2. alex says:

    Nice design, good to see some analog electronics on here. Initial observation is that you have two large FETs in parallel to provide the variable current regulation for the load. FETs in parallel rarely share the juice fairly, always best to add a bit of R in each FET string to encourage them to have more similar resistances…

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