[HomeBrew] Variable Power Supply - current protection

[Helmut Usbeck]

Don't remember if the LM317 has s/c protection, don't have the data sheets
here at home.  One device I am using in a small 3 amp supply for a QRP
transceiver I have is a solid state resettable fuse. It's basically akin
to a triac.  Draw more than 3 amps and it "opens" up.  Remove short or
overload and power up and down and it resets.  The 3 amp number is RGE300.
There are other current ratings available.  It wires into the circuit as
if it were a regular fuse.  Looks like a large monolithic cap.
Two terminals.  Works fast unlike circuit breakers, or slo-blows.  Mouser,
Digi-key and Allied has them.
-Helm.  WB2ADT

On Tue, 7 Jan 2003 eddiehan@bigpond.net.au wrote:

> ** HOMEBREW REFLECTOR - Please do NOT cross-post messages to multiple mailing lists on the "To:" or "CC:" line of the e-mail message. **
>
> Am building a normal variable voltage power supply for breadboarding using LM317
> and would like to implement an electonic fuse and or short circuit protection.
>
> Not sure if s/c protection is built in to the LM317.
>
> The idea is to be able to vary the overload current trip say up to 1Amp.
>
> Anyone know of a web address or simple circuit to achieve the above.
>
>
> Eddie
>
> VK2BEH
>
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