DC trigger/relay for power conditioner/filter?anyone?

[Lance]

has anyone a suggested high current electro-mech relay via a dc trigger (12 volts) that I can build into my power conditioner/filter projects so it can be activated via my HT/preprocessor for the amps on a separate dedicated ac line....
and/or with a timer circuit to allow sequencial turn off/on after power surges/brownouts (thunderstorms,etc)
Any help would be very greatly appreciated

[Oscar]

Originally posted by Lance
and/or with a timer circuit to allow sequencial turn off/on after power surges/brownouts (thunderstorms,etc)

What I've been thinking about is a sequential turn on/off with a delay between the different outlets of the filter. When powering on equipment one should always start from the end and go forwards (source first, power amp last). I'd like to turn on all my components with one switch - the one in the filter. Maybe it's not at all necessary, but it'd be a nice touch if, when pushing the power button of the filter, there was a two second delay between the switching on of the outlets. And ideas how this could be done? Or is it completely unnecessary?

[JOE DIRT®]

a sequential delay circuit can be made easy enough with a group of 555 timers and they have enough current to drive a relay

DIRT®

[Matttcattt]

i would use a PIC microconntroller, but this would make things overly complicated. a 555 timer with a decade counter would work, with the decade counter using transistors to run the relays. this would give a max of 10 outputs.

[Helix]

dont even need 555's

Just transistors to turn on the relays, timed by RC circuits

[JOE DIRT®]

matt I`m aware of how a pic can do this as I am a programmer...tried to keep it simple for home use and the 555 timers are so cheap that you would not need any transistors yeilding a more economical design


DIRT®

[moamps]

delay sequence idea

R1=22k, R2=220k, K1on=ca 1s, K1off=ca 10s (first on, last off)
R3=47k, R4=100k, K2on=ca 3s, K2off=ca 8s
R5=100k, R6=47k, K3on=ca 5s, K3off=ca 5s
R7=220k, R8=22k, K4on=ca 7s, K4off=ca 3s (last on, first off)


Regards

[mhennessy]

This would work fine, but could be even simpler - you don't need the schmitt triggers. Re-wire the transistors to be emitter-followers.

That said, you'd want to double-check the off-timings because the relay obviously needs fewer volts to hold on. But this would just require the usual prototyping and experimentation before you built it for real...

HTH,

Mark

[moamps]

Originally posted by mhennessy
This would work fine, but could be even simpler - you don't need the schmitt triggers. Re-wire the transistors to be emitter-followers.

Hi, Mark

Schmitt triggers are used for fast switching on-off, what is important when power relays are controlled. Also, input current in schmitt's are very small, i.e. t(on) and t(off) are better determinated and aren't depend of characteristics of relays.. Price of 4093 is under 0,5€.

Regards

[mhennessy]

Originally posted by moamps
Schmitt triggers are used for fast switching on-off, what is important when power relays are controlled.

That's a good point - I'd forgotten that these were switching the mains directly. Actually, you might be able to to advise me on something - I'm currently prototyping a circuit to switch my GainClone monoblocks on/off - it's just some logic for the front panel pushbutton and the 12V trigger input, switching a relay...

For various reasons, I'm using a current source to power the relay coil. Do you think that this is bad idea for the reasons you mention above?

The current source is switched on quickly by the logic, but the inductance of the relay coil will probably slow down the pull-in...

Another thing - I'm wondering about a subber for the relay contacts - say 10n (class X) in series with 100 ohms. I'm undecided because the cap is physically large, and about the same price as the relay! Any experiences here?

Cheers,

Mark