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Rare diagnostic tool ?


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I took this picture myself.... sure hope you guys keep your crowbars up to snuff!

327C7D57-36A2-47C6-A573-73B547F38965.jpeg

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2 hours ago, oleman said:

The first equipment I ever worked with that had  a high voltage crowbar was in 1966 and everything has to be tested.

Yes, it appears funny, but a crowbar circuit is a circuit that protects components should they experience an overvoltage or a surge. Basically a surge protector. Just FWIW!?

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35 minutes ago, TomH said:

crowbar circuit is a circuit that protects components should they experience an overvoltage

Any circuit that uses a crowbar as a fuse is more juice than I want to be around. ??

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Actually, most modern commercial equipment  has a super fast blowing high amperage fuse in the main DC circuit. Our transit bus based RV has an 800A fuse, so when the people I hired to move the Bus reverse jumped  the 24  Volt system. The fuse blew instead of the batteries exploding. That type of fuse will blow in a few micro-seconds at its current rating.  Those non-techs the company sent to repair the bus, were really lucky because when 2 EA of 8D batteries explode will make a very loud bang. This type of fuse can replace some crowbar circuits.  In the old days fuses were not very fast so they used a transistor circuit to quickly blow a slow fuse. The device of choice was an SCR or silicon controlled rectifier. They are still used in large amperage rectifier (Think analog welders)  circuits BUT switch mode power supplies have made them rare. 

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