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Bryan 14th September 2005 06:29 PM

Timer Relay
 
Hey Guys,

So I've been searching, and I can't seem to find what I need (for a reasonable price).

I need a relay which will switch on after about 30-60 seconds.

Basically, I need to provide fillament warm-up before the hv kicks in. So, I would like to use a relay that after a set time-point will switch the mains on to the HV trannies. The relay should be powered by 120VAC, and be able to switch either 120VAC or ground the center tap of the HV tranny.

I've seen several octal type delay relays, but these are expensive (~$50). Is there any type which is in the $10-20 range?

Thanks,

Bryan

arteitle 14th September 2005 10:42 PM

How about an Amperite time delay relay tube? They're retro and tubelike, though you may only be able to use one to switch another higher-capacity relay. You can find a datasheet here.

astouffer 14th September 2005 10:46 PM

Every commercial relay is going to be fairly expensive. You can do the delay with a 555 timer.

http://555-timer.clarkson-uk.com/operation/delay.html

The 555 can sink 200ma so a transistor may not be needed. Make sure the relay coil has a diode across it to supress any spikes. You could easily power this from the 6v filament line. Anything from 6-12v should work.

woody 14th September 2005 11:41 PM

Have you considered using damper diodes such as the 6d22s
for the rectifier? With there slow warmup time this might be all the delay you need.

ray_moth 15th September 2005 03:18 AM

Quote:

Have you considered using damper diodes such as the 6d22s
Yes, TV damper diodes give you both a delay (30 seconds) AND a soft start. Using one of these, in series with an SS diode bridge, I am able to use a B+ fuse of only 500mA (fast blow) even though I am charging a total of 700uF worth of reservoir and filtering capos through it. The fuse has never blown! I use my 6D22S in the negative line, so there isn't a dangerous voltage at the top cap (the cathode). You lose only about 15v.

You can also use these diodes succesfully as one half of a hybrid bridge, or as a full-wave rectifier if your HT secondary winding is centre-tapped. However you lose a lot more volts that way.

sst4270 15th September 2005 06:40 AM

Just built my first amp
 
Just built my first amp. Rick Spencer's Mini SE Amp from 4-04 AudioXpress. The circuit calls for just such a relay.
I bought it from a local appliance parts store just like the author suggested. Paid $10.50.
It is the ICM102. Data sheet attached. Works great.

EC8010 15th September 2005 11:45 AM

I've tried measuring the warm-up time of 6CL3 and found it was exactly the same as EZ81. 11 seconds. Not what I expected, but there you are.


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