Amperite delay relays

[engels]

In my never ending search for a better B+ delay I've decided to try Ampterite delay relays. I think making a SS device in a shape of a tube is at least funny, so I'd go for it. (Hope someone makes an octal 4558 soon!)

There are many threads mentioning the subject but (singing) I still haven't found what I'm looking for.

The Amperite's datasheet doesn't give the heaters' current ratings and somewhere I've read that it's adviced to turn the relay off after it closes to save the heater. The deatasheet keeps silence about that.

And I'd like to see some schems - although it seems obvious I'm sure there are bugs I'm not aware of (like that above mentioned thing with turning it of after it closes).

Amperite tube-shaped Delay Relays datasheet

Who uses them?

[Conrad Hoffman]

I think all the old Tektronix tube scopes like the 535 and 545 used them. Seemed to work just fine, as my Teks have been going strong since the '70s.

[DigitalJunkie]

I have used one once in a prototype..It worked great.

You have to leave the heater connected,or else the contacts will open up again..

It's basically a bi-metal switch (like a thermostat),with an attached heater.

[pmillett]

The Amperite datasheet does give the heater rating, indirectly: 2 watts. So ~320mA at 6.3V.

A comon scheme is to use a relay in addition to the delay relay to de-activate the delay relay heater after power-up. This allows the delay relay to cool so that if you turn the power off then back on, you get the full power-up delay.

I found a thread on a different forum with a schematic:

http://www.diytube.com/phpBB2/viewto...d790598f7e3af2

Pete

[Tom Bavis]

30-40 years ago, the Aperite datasheets DID suggest using a latching relay which also removes power to the delay tube heater. Four advantages I can think of:

1) saves heater life
2) prevents contact chatter, as it latches on first contact
3) lets relay cool for next operation
4) relay can have greater voltage / current rating than delay tube

I like the Potter & Brumfield T92 relay - it's rated for 380 VAC and 30A, easy to mount and not too expensive.

[Jeb-D.]

A comon scheme is to use a relay in addition to the delay relay to de-activate the delay relay heater after power-up. This allows the delay relay to cool so that if you turn the power off then back on, you get the full power-up delay.

On the flip side, the audio tubes will be warmer as well, in a turn-off turn-on circumstance when compared to a cold start. So the delay shouldn't have to be as long.

[cbutterworth]

I used an Amperite in my Aikido for quite some time. I used one of the old schematics from Amperite that only had the delay tube powered while it was timing. Basically:

1. The power is applied to the Amperite
2. When the timer trips, it switches an Omron DPDT relay to which the PSU is connected.
3. When the Omron tripped, it switched on the PSU, the other Omron contacts took switched to open and took the Amperite out of circuit.

I can look-up the schematic for you and send it.

Charlie

[Steven-H]

Gents,
I did use that schematic that Tom McNally suggested on DIYtube to pre-heat before I switched on my 83 Rectifier. Works well - just make sure you have a nice quiet relay or you'll get some hum.

-Steve

[engels]

Thanks a lot for the tips, and how come I've missed the 2W heater rating? I was probably thinking it's a plate dissipation

Now isn't that weird that you have a delay relay activating another relay? If you have a relay already in a circuit you can hook it up with some - 555 and save space. Although any DIP-8 looks bad inside a tube chassis. That's why I'd ask for an octal 555 as well.

At some point I've thought I'm going to order a couple of delay relays and stick them in without additional relays in a standby switch position.

But some posters say you cannot wire them to HV. For example here's something by coresta :

Hi ! I'm using XT90As from the former Thomson-CSF in my OTLs . These could be subs of 6NO90 if they do exist ! But caution :
Don't use these to switch directly HV !! As TEKTRONIX did , they turn a low voltage relay on to avoid arcing .

So the second relay is a must?

[Steven-H]

Dunno - I used mine to ground out the CT on the HV line - been fine for over a year.