Suitable relay for delay cicuit

[peranders]

Diodes for relay coils are very unsensitive. You can use almost anything as long as the voltage rating is enough.

[peranders]

Originally posted by Nuuk


Sorry Sébastien,

I didn't explain fully. The idea is to short (to ground) the output of the pre-amp/buffer until the power supply has 'settled'.

Originally posted by Nuuk

Thanks again. Is there a formula for working out the resistor value?

If your preamp has 100 ohms at least as output impedance and this is accomplished with a resistor, it's safe to just short the output. If you aren't sure add 100-220 ohms to have in series.

[Nuuk]

Thanks again Per-Anders. I have now written up the project here

As regards the extra output series resistor, presumably this would be put between relay and ground so that it does not alter the circuit after power up.

[peranders]

The relay contact should ge between the power amp input and ground. The extra series resistor should go between the preamp and the power amp.

Check how I have done the mute of my DAC

http://home5.swipnet.se/~w-50674/hif...ema_sida_4.pdf

Nuuk, if you output IS short circuit proof, it's no harm to brutally short the output to ground. If you aren't sure,100 ohms extra in series is nothing compared to the rest.

[Nuuk]

The relay contact should ge between the power amp input and ground. The extra series resistor should go between the preamp and the power amp.

If you aren't sure,100 ohms extra in series is nothing compared to the rest.

I'm a bit confused! If you add 100R in series with say the 68R on the output of the transistor buffers that I am using, doesn't that change the characteristics of the buffer by limiting the output current? If not why is 68R specified and not 168R (or 150R)?

[peranders]

You must also consider the load in th other end. If it is 10 kohms 68 or 168 ohms will make not much difference but if you have 68 ohms, this will be enough I think for current limiting at startup.

Did you check how I have done my muting?

[Nuuk]

Did you check how I have done my muting?

IF I understand it correctly, you short the outputs of the OPA627s to ground after the 51R resistors.

[postpunk]

OT: Nuuk, I don't get any pop at all when I switch on the buffer or my gc. I builded a similar gc for my brother, and he gets loud pops. Why is that :?:
Edit: Now that I come to think about it, I have used 8 ultrafast diodes in my gc, while my brother's uses a standard bridge. In my buffer I use 8 byv27-150.

[Nuuk]

OT: Nuuk, I don't get any pop at all when I switch on the buffer or my gc. I builded a similar gc for my brother, and he gets loud pops. Why is that :?:

Do you have your power amps switched on when you power up your buffer? Or do you power up both together? If the latter, are you using an LM3886 or similar chip with a muting function?

[peranders]

Originally posted by Nuuk
IF I understand it correctly, you short the outputs of the OPA627s to ground after the 51R resistors.

Yes, the opamp can without problem cope with that.