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Automatic line level detection

Thommy, unfortunately the force on operation is pretty instantaneously off when used as you describe.
You would have to hold the force button for the whole time it takes to start the DAC. Once playing it would auto power off nicely so long as the button was released once started.

Stephan, force on does not charge the capacitor, it just powers the relays.

Of course with a little bodging and it could!

I do use one of these thingys to auto power off / on my Silly DAC.
In my case I have a Rpi running Squeezeplay as the first section of the DAC. The pie is always powered on and runs a script to repeatedly pulse a general I/O pin high when a valid data stream is present. This pulse is connected to the thingy just as a single ended source signal would.
So my DAC and amps all auto power off/on.
 
Stephan is probably thinking of applying 12 volts via a momentary to X4-2, which would of course charge the capacitor and power on the DAC.
You would have to bodge your own 12v pickup point as the board does not have a readily avaliable pin.
I would suggest 100R in series to limit the charge rate.
And in this case ensure both force on and off were never applied simultaneously.

Just a maybe here, but perhaps momentarily linking X6-3 (power off LED) to X4-2 would do the job. It would charge the capacitor at 20mA right up to the point the detector board was on.
You would have to play around and see what happens.
 
That's a very elegant way of doing it.

I'm using Arduino for channel switching in addition to the pi (both always on) so maybe it could be set up to send a similar signal for a minute or so after the input select button is pressed.
 
oops, crossed posts.

Bodge is also easy and i hadn't incorporated a forced standby switch anyway. Thanks for giving me both options :)
 
So I could grab the output of VR1 and put a momentary switch & 100R between that and X4-2 to charge the cap?
 
Yes posting overlap, I was probably still editing so re-read to be safe.

If you use a pulse train from the Arduino you only need a slow train. I think mine was half second on three seconds off. Make sure the pulse is connected just as the audio signal would be as you need the decoupling capacitors in circuit else your going to effectively whack 12v back to tje Arduino GPIO!!!
 
thommy said:
So I could grab the output of VR1 and put a momentary switch & 100R between that and X4-2 to charge the cap?
Click to expand...

VR1 is off the 6 volt regulator, I would use the 12 volt reg. Say pickup realy coil A1 terminal, through 100R, through momentary and on to X4-2
 
and again...

X6-3 would carry 12v so it should work. Thats probably the best solution. I have an led ring momentary switch, could connect the led pins to X6-1 & 2, the switch terminal between X4-2 and X6-3. Then the ring will glow when it's pressed if the idea works.
 
thommy said:
and again...

X6-3 would carry 12v so it should work. Thats probably the best solution. I have an led ring momentary switch, could connect the led pins to X6-1 & 2, the switch terminal between X4-2 and X6-3. Then the ring will glow when it's pressed if the idea works.
Click to expand...

Could be neat, finger crossed that the capacitor charges enough befor the relays power on.
Of course twiddling with our Arduino could be fully automatic which seems cooler.
 
Bemused said:
Stephan is probably thinking of applying 12 volts via a momentary to X4-2, which would of course charge the capacitor and power on the DAC.
Click to expand...

Ah that's it. Actually never got round to doing mine but remember having this same conversation now !
 
I've been waiting for casework since Nov 2013. This week I finally got set up with a CNC router so it's full steam ahead on about 10 projects from now on :)
 
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