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Old 31st January 2012, 04:28 PM   #1
diyAudio Member
Join Date: Oct 2004
Location: Denmark
Default Delayed on-fast off board

Board for delayed on-fast off. Intended for use in a headamp I'm working on.

Board is not completely done yet. Might do a few changes to the layout but nothing major. Mainly tidying up the silkscreen, adding text on inputs/outputs. Also, T2 and T3 are supposed to be TO-92 FETs, 2N7000, but as I'm not home at the moment I dont have access to the right FET models. Taking their place are 2 x EBC TO-92 BJT's. Pinout corresponds to the 2N7000 FET's(E=S, B=G, C=D). Will be fixed in the weekend when I get home.

Runs on +12V DC.

Has a 3 second delay before activating the relay and an AC sensor circuit to turn off the relay immediately when the supply is powered down.

Based on ideas taken form DIYA and various other sources on the net.
Attached Images
File Type: png LTSpice-Anti-Pop-Plop.PNG (31.4 KB, 57 views)
File Type: png Simulation-Anti-Pop-Plop.PNG (30.7 KB, 59 views)
File Type: png Schematic-Anti-Pop-Plop.PNG (36.5 KB, 59 views)
File Type: png Layout-Anti-Pop-Plop.PNG (114.7 KB, 57 views)

Last edited by Neutrality; 31st January 2012 at 06:22 PM.
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Old 31st January 2012, 06:34 PM   #2
diyAudio Member
Join Date: Oct 2004
Location: Denmark
Getting close to done.

Only thing left is replacing the BJT's with the correct FET's.

Removed the ON LED, served no real purpose.

Also changed the way the signal goes through the relay. Now in OFF state, output to the headphone will be grounded instead of floating.
Attached Images
File Type: png Schematic-No-Thump-Final.PNG (35.5 KB, 50 views)
File Type: png Layout-No-Thump-Final.PNG (108.3 KB, 28 views)
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