Delay on loudspeaker switch on. - Page 2 - diyAudio
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Old 16th December 2002, 03:11 PM   #11
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I've just re-read your post and noticed that I confused ne555 (timer) with NE5532 (op-amp)!

You could use a 555 timer for a deley on power-up but it won't disconnect the speakers immediatly on power-down, so thumps could still get through. The reason is that the power supply capacitance will hold-up the voltage rails so the 555 won't see that power has been disconnected.

I guess you could use a second bridge rectifier to power the delay circuit and just use a small electrolytic to hold-up the 555's rails for just a few seconds, say 10uF -> 100uF.

Nice one,
David.
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Old 16th December 2002, 04:30 PM   #12
jleaman is offline jleaman  Belgium
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Actualy. you put the relay circuit befor the capacitors. : O ) and i was going to use a simple 555 ic with my murcury wetted relays. people say it will work just perfect. It wont provide speaker protection against dc. but for the power on and power off thumps it will be just fine.
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Old 16th December 2002, 04:34 PM   #13
fcel is offline fcel  United States
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David,
So, can you suggest (meaning part #) an op-amp to use for the circuit that you mentioned. I would like to build one. Thanks.
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Old 16th December 2002, 04:51 PM   #14
jleaman is offline jleaman  Belgium
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Timmer ic 555.
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Old 16th December 2002, 05:04 PM   #15
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Fcel,
I used a plain 'ole 741 - although just about any op-amp is suitable.

Nice one,
David
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Old 17th December 2002, 07:53 AM   #16
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JasonL - your application is spot on for what I want to do - have you got a circuit diag, or is it still brewing?
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Old 17th December 2002, 04:02 PM   #17
jleaman is offline jleaman  Belgium
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Here i am going to ues this exact circuit.
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Old 17th December 2002, 04:03 PM   #18
jleaman is offline jleaman  Belgium
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Im gonig to use this for my temp controler. Ill use a temp controler to output voltage to use this circuit. Main idea is to tell me when my aleph 2's are warmed up and ready to use.
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Old 17th December 2002, 05:06 PM   #19
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Just found this version, which is more like what I want - a monostable delay on version. i.e. - I apply power, there is a delay and then pin3 goes high and remains so
http://www.andy-clarkson.me.uk/555/frames3.html

JasonL - is that what your circuit's doing too? I'm not well up enough on the ins and outs to quite see what's going on there.
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Old 17th December 2002, 05:36 PM   #20
lykkedk is offline lykkedk  Denmark
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The voltage is 9vdc right ?
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