audiosignal
Active Member
Does anybody knows of anything (buy or built) that will do the above? Regular timer devices don’t cut it as they will turn things off at preset time, sound or no sound.
External device to turn power off when no sound is detected for 1 hr or longer
- Thread starter audiosignal
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restorer-john
Addicted Member
Yes. I designed a simple unit around 20 years ago for that exact purpose. It was to fall asleep playing CDs of relaxation music and switch off the system when the music finished. I had a time constant of about 10-15 mins afterwards, but it could be anything realistically.
I'll dig it out and post the schematic. I even made a PCB for it and I know I've still got the artwork someplace if you are interested in making one yourself.
Ran on a wall wart and had a 10A 2400W rated relay inside.
audiosignal
Active Member
Great. I would like to see it.
My Polk sound bar turns itself off after being muted for ten minutes.
(Probably not much help to you though.)
(Probably not much help to you though.)
arts
Addicted Member
I'd really like to see this R-J. On a sort of related note,my GF wants me to design something of a similar nature that will give me a shock when I start snoring.I'm sure you can understand my reluctance....
twiiii
Lunatic Member
Mcintosh uses a logic circuit to turn on components in a system. Normally you turn on the HT processor or pre-amp and everything else turns on sequentially and when you turn off they turn off. Now the MVP891 has its own built in computer so it will turn off after a brief time with no disc present or if a disc is finished. I bet you could reconnect the power control circuits to make the MVP 891 the master unit and everything else its slave.
cpt_paranoia
Addicted Member
High gain buffer, feeding re-triggerable CMOS MMV, which then controls a relay?
restorer-john
Addicted Member
OK, so I turned the house upside down and found the little bastard for you guys. Here it is:
9VDC wall wart powered, puts out about 12V. Proper EI transformer for isolation. Small ABS/Plastic box
Prewired extension cord, only cost a few dollars- cheaper than buying plugs and sockets.
Added a turn on/start button. Otherwise catch 22- you need an audio signal to turn on the system... Can add an instant-off too, if you want.
Chassis mount RCA sockets. Strictly only one is needed, the load is insignificant, but I balanced it anyway. The signal simply comes from an unused tape-out or even a video signal will trigger it. A few mV is all that is needed. At one point- I used it to turn on the whole AV system when the VCR (that's how old it is) powered up and sent out a video signal.
Power cable straight in, zipped tied on other side to prevent pulling out. No room for exotic cable clamps in this tiny box.
RCAs, ready to go
The inside story. Omron/Fujitsu 10A 250vAC 12v coil relay, switching both active and neutral. Live part of PCB and tracks isolated, insulated with elephant-hide or similar on track side.
Three TO92 transistors, scavenged resistors from an old radio (I remember doing that) and yes, even back then, nice little Nichicons. Shielded cable to the RCAs is probably unecessary.
Running production change
(the old days of hand taped PCB prototypes)
A closeup from above
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restorer-john
Addicted Member
Reserved to upload details
restorer-john
Addicted Member
Reserved to upload schematic & pcb
(I have seen my original bits of paper with my design in the last year or so in a box someplace, if I can't find it, I'll redraw the schematic)
These days, I'd probably add an LED for power-on and two momentary SPST buttons, one for instant-on and instant-off.
Block diagram was basically high gain front end, rectified, charge cap, intermediate buffer and relay driver. Discharge blocking diode and RC calculated timeout after no signal can be varied to whatever you want with component values. Instant-on button simply charges cap via resistor to +. Instant-off can be discharge cap via resistor-switch.
(I have seen my original bits of paper with my design in the last year or so in a box someplace, if I can't find it, I'll redraw the schematic)
These days, I'd probably add an LED for power-on and two momentary SPST buttons, one for instant-on and instant-off.
Block diagram was basically high gain front end, rectified, charge cap, intermediate buffer and relay driver. Discharge blocking diode and RC calculated timeout after no signal can be varied to whatever you want with component values. Instant-on button simply charges cap via resistor to +. Instant-off can be discharge cap via resistor-switch.
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