Rene Schmitz 555 adsr debug/problem

sonrie69 · Joined: Apr 05, 2013 Posts: 7 Location: rosario

hi people.... i built rene's 555 adsr .. i am having problems.. i use proteus for simulating the schematic.. in proteus everything is find.
but when i built i find some problems.
the output of the tl081 is up when gate is down.. but when gate is up, the adsr work well...
i measure the volt in the tl081 and i find that is 0.3v against the 0.6 v in proteus... is possible that this difference is the issue why the output is up without gate in???

i attach the schems and the pcb

new adsr 555 pbc.jpg

Description:

Filesize:

338.54 KB

Viewed:

230 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

new adsr 555 schem.jpg

Description:

Filesize:

1.34 MB

Viewed:

404 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

adsr2.png

Description:

Filesize:

9.04 KB

Viewed:

355 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

JovianPyx · Posted: Sat Apr 06, 2013 12:02 pm Post subject:

The output of the TL081 should be identical to the voltage at it's non inverting (+) input. This should be measured using a good DVM or DMM or oscope (high impedance). If not, check for solder problems around the TL081 and it's connections.

sonrie69 · Joined: Apr 05, 2013 Posts: 7 Location: rosario

hi JovianPyx, thanks for the answer.. i checked the connections ...actually, when the gate in on, the tl081 works fine, and the output equals the + input...
it's like the voltage on + input is out of range so the tl081 output is V+. i am doubting about the my pcb design..

another thing i find is : on R5 the voltage is 0.04 volts, but in proteus is .12 volt. i tried to enhance the power there by reducing R5 but (in my little experience) i doesn't help.. i like the Q2 takes more power on the pcb than the simulation..