HT delay pcb...

[HVfanatic]

So,

next: Morgan Jones describes on page 375 a useful circuit. Yes, I'm sure it's possible to build something with ne555 as well...

My question: Does anyone have a pcb for this circuit?

Other solutions are also highly appreciated, but a pcb would be very nice... I would also be interested, how other members solved muting relay and delayed HT...

Regs, Dirk

 

[KatieandDad]

If all you want is a delay I wouldn't go as far as a 555, just a simple RC and a transistor would suffice.

 

[HVfanatic]

Hi,

I want some more comfort: 1. Delay HT, then open mute relais... I Case of power off: First mute, then HT off....

Dirk

 

[roline]

I just use a pass tube 6CG3 diode slow start ~20 seconds, The heater power 6.3 volts is easier to switch than 500V....

 

[Alkis]

Hi Hv,
where are you going to hook up the mute relay?

 

[tuhkam]

Hi!
I use a transistor based B+ delay for my EL84 SE, but no mute relays. I don't miss them since the amp is like "muted" without anode power anyway. If the power comes on then the volume ramps up softly within a couple of seconds.

 

[HVfanatic]

Hi,

mute relais on output. It's a preamp.

Dirk

 

[Alkis]

You could use a CL-90 which is often used in amplifiers. Connected between the 230V line and the primary of your power transformer if you have seperate ps dedicated for HT. If not, connect the CL-90 between the HT output of the transformer and the first element. Then use a 20 sec delay circuit/relay if you wish, to shortcircuit the thermistor. The resistance at this point will be bellow 1 Ohm, so no pop noise at all, just the click noise from the relay. Remember that you will have to wait at least 20 mins for successively starting-ups, but this will be not a problem. At an other point you can exchange the delay circuit with a delay relay working straight at 230v and you are done. That's what I've done in my case.

Alkis.

http://www.ge-mcs.com/download/temperature/920-325C-LR.pdf

 

[Alkis]

But again, it's a preamplifier. So why bother with delayed HT? The preamplifier starts before the end plf and shuts down after the plf is off.

 

[HVfanatic]

Hi, CL90 ist softstart. But fast switch on/off in hot mode is bad. I wan to be sure there is no HT if there is no heater. And think: Your girlfriend may (ab)use the equipment. Mute is absolutely required not to fry your solid state poweramp input. What is "plf"

Dirk

 

[Alkis]

Then use an output relay with a small disc-shaped capacitor connected between the contacts, in conjunction with a delay relay. I presume you don't have an output transformer.
And give your girlfriend the proper directions
plf / amplifier

 

[HVfanatic]

... but the cap will delay turnoff! How do you solve this?

Dirk

 

[Alkis]

????? ????? ?????.

 

[HVfanatic]

Cap delays switchon, but also switchoff - correct?

 

[TheGimp]

A diode across the resistor will discharge the cap rapidly at power off. Simple CPU POR trick.

 

[HVfanatic]

Hi,

I think, I have a fundamentalmisunderstanding: A (quite huge) cap takes time to build up the voltage. So relay is delayed. But how can i use the diode? Forward bias would prevent the cap getting charged, reverse bias will do nothing. Can you post a schematic to clarify?

Dirk

 

[TheGimp]

Reverse bias will do nothing during the charge phase (power on). However, at power off the diode will become forward biased and rapidly discharge the cap.

 

[Jaap]

Zeitsteuerungs-Bausätze - im Conrad Online Shop günstig kaufen

 

[HVfanatic]

Hi TheGimp,

please post a schematic, I think, I have a misunderstanding:

Reverse bias will do nothing during the charge phase (power on). OK

at power off the diode will become forward biased NO!!! Voltage stays reverse based, but will decrease...

Where is my misunderstanding???

 

[TheGimp]

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