ampage archive

Vintage threads from the first ten years

Re: question for Gary (aka Glasman)...

 

2/28/2005 3:14 AM
Ian Anderson	Re: question for Gary (aka Glasman)... hi Dave, long time eh,     they're 12v DC relays, my transformer has two 12v taps which I thought were DC when I bought it but it can't be can it. I could always go back to Maplins and exchange it if there's a better solution (?)     Cheers... Ian

 

3/3/2005 3:08 AM

Dave H

Is the transformer 12V-0-12V ? If you use a two diode full wave rectifier and smoothing cap the voltage will be 15V DC or more but it’s not a problem just put a resistor in series with each relay to reduce the voltage to 12V. A 9V-0-9V transformer would be about right for a 12V DC supply. The simplest circuit would be a transformer with a single 9V winding, half wave rectified and smoothed with a diode and cap. It’ll have more ripple but it’s good enough for relays.     Dave

 
 

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3/3/2005 4:56 AM
Ian Anderson	Dave, its actually got two seperate 12v taps (four contacts).     ... Ian

 

3/3/2005 5:22 AM

Dave H

Now you’ve got too many choices Connect the windings in series and use two diodes and one cap (like a B+ supply) or connect them in parallel and use a FW bridge or single diode half wave rectifier. Are the windings marked 0 12V, 0 12V ? If they are connect the centre 12V and 0 terminals together to wire in series (it will measure 24V end to end). To wire in parallel connect 0 to 0 and 12V to 12V. If you get them inverted it will fry. If a single winding can supply enough current it would be safer to just use that rather than the parallel connection. But you know all this right?     Dave

 

3/3/2005 7:10 AM
Ian Anderson	quote: "But you know all this right? "     err, yeah, of course     I'll try your suggestions out Dave, cheers mate.     ... Ian

 

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