4.5vdc relay?

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mark Lister
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Joined: Wed Apr 16, 2008 9:44 am

4.5vdc relay?

Post by mark Lister » Wed Apr 16, 2008 9:53 am

I am trying to use an output from the throttle pot on my car. The o/p is 0 to 5v. The trouble i have is that I only want an o/p when the voltage is 4.5v and higher. This o/p then needs to open a relay until it drops below 4.5v again. The relay is only for a signal so no power involved. Any ideas please??
Thanks, mark

Posts: 72
Joined: Sun Mar 09, 2008 3:24 pm

Re: 4.5vdc relay?

Post by Biffo » Fri Apr 18, 2008 7:48 pm

Might be an idea to use a 'switching regulator' ? there are a fair few about that kick in at 4.5 volts.

Simon (Webmaster)
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Location: Nottingham, UK

Re: 4.5vdc relay?

Post by Simon (Webmaster) » Tue Apr 22, 2008 7:06 pm


If you need the relay to switch on at an exact voltage you will probably need a comparator circuit. Search the web for more details (I'll try to put some info in the technical data section when I get time). Essentially you will need to connect the trottle pot voltage to one input and a constant reference voltage to the other input. The output will drive the relay through a transistor.

Sorry I haven't got time at the moment to give more details.
Simon Carter
Electronics 2000

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