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Coriolis
Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark
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 Posted: Wed Aug 06, 2008 5:23 am Post subject:
Ian Fritz - Delayed Pulser...having trouble with these
Subject description: Anybody built them? |
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Right.
A while ago, I built those nifty AD/AR eg's by Ian Fritz - see this thread:
http://electro-music.com/forum/viewtopic.php?highlight=ian+fritz&t=24308
No trouble, they still work. But then I wanted to add those Delayed Pulsers also mentioned in the above thread.
I've done 2 versions: 1 on stripboard and 1 on pcb.
Neither seem to work. Stripboard version let the magic smoke out of a couple 7555's though, and something also smells very hot on the pcb version.
Symptoms:
-7555's get hot when x out of DelayedPulser is connected to x in of AD/AR.
- X out of Pulser read 9.37V, and stays there.
- AD/Ar doesn't work when the abovementioned x'es are connected.
And a question:
Do I feed both the AD/AR and the Pulser a trigger simultaneously, or is it enough to trig only the Pulser, if I want to use it's functionality (just as I only feed the eg if I only want normal eg)?
I have of course checked my layouts many times (but never say never, right?).
Anybody? Ian? 
C
Edit: Oh, and on my layout of the AD/AR, there are 2 x'es on the board...these are NOT the "x" inputs in Ian's schematic, but show where the pots connect. I could have made that somewhat clearer... 
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frijitz
Joined: May 04, 2007
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Posted: Wed Aug 06, 2008 7:23 am Post subject:
Re: Ian Fritz - Delayed Pulser...having trouble with these
Subject description: Anybody built them? |
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| Coriolis wrote: |
-7555's get hot when x out of DelayedPulser is connected to x in of AD/AR.
- X out of Pulser read 9.37V, and stays there.
- AD/Ar doesn't work when the abovementioned x'es are connected.
And a question:
Do I feed both the AD/AR and the Pulser a trigger simultaneously, or is it enough to trig only the Pulser, if I want to use it's functionality (just as I only feed the eg if I only want normal eg)?
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Christian --
Hmmm ... sorry about the trouble.
I've recently reworked the EG + Delay Pulse. Bridechamber will be soon selling a board for this, which I have tested.
The only change from the original design were (1) changed timing caps to 2.2 uF and (2) added 1k resistors in series with the two pots. I had troubles when the pots were turned to zero. (My original unit didn't have any problems in this regard.)
Are you saying that you only get the overheating when the delay unit is connected to the EG? Doesn't seem likely with the 100k resistor between them.
To fire the pulser you only need to feed its input. But feeding both shouldn't hurt anything.
Did you post the layout of the pulser?
Ian |
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Coriolis
Joined: Apr 11, 2005
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Location: Stilling, Denmark
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| Posted: Wed Aug 06, 2008 7:51 am Post subject:
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Hi Ian
| Quote: | | Are you saying that you only get the overheating when the delay unit is connected to the EG? Doesn't seem likely with the 100k resistor between them. |
It seems so. I haven't seriously probed around the circuit yet, but will of course. I'm no wizard like you, but it seems to me there is something fishy about those 9.37V. It looks a lot like the 2/3 supply voltage that the 7555's input can take, right? Edit: Strike that, just looked at the datasheet and I'm talking nonsense...
| Quote: | | I had troubles when the pots were turned to zero |
What sort of trouble, may I ask? I've used 1M pots in both positions, as per your original schem.
And no, I never posted a layout and won't, if you'd rather I didn't (now that you'll be selling them). It's probably faulty anyway...
Let's say I had a scope (which I don't): If I injected a trigger into the trigger input of the Delayed Pulser, what would I see coming out of point x exactly? A stretched and delayed trigger pulse, right?
C
[/quote]
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frijitz
Joined: May 04, 2007
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| Posted: Wed Aug 06, 2008 8:48 am Post subject:
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| Coriolis wrote: | | Quote: | | I had troubles when the pots were turned to zero |
What sort of trouble, may I ask? I've used 1M pots in both positions, as per your original schem. |
It looked like the 555 didn't like the pins 6 & 7 connected directly to the supply.
| Quote: | | And no, I never posted a layout and won't, if you'd rather I didn't (now that you'll be selling them). It's probably faulty anyway... |
I wouldn't mind your posting the layout. I'm not trying to protect the design (except for commercial use).
| Quote: | | Let's say I had a scope (which I don't): If I injected a trigger into the trigger input of the Delayed Pulser, what would I see coming out of point x exactly? A stretched and delayed trigger pulse, right? |
Yes, exactly.
Ian |
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Coriolis
Joined: Apr 11, 2005
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Location: Stilling, Denmark
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| Posted: Wed Aug 06, 2008 11:02 am Post subject:
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Hmm...just tried feeding a trigger into the pulser and taking the output straight from that into a vco. Same non-results + magic smoke!
This without a connection to the eg board.
Seems like loading the pulser does this to the chips...
C
Edit: Thought of something - do you know if the pulser works on +/- 15v without mods? Cause that's what mine are running/dying on...
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Coriolis
Joined: Apr 11, 2005
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Location: Stilling, Denmark
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| Posted: Wed Aug 06, 2008 11:47 am Post subject:
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Ok - probing with a DMM!
Findings:
- All chips are geting correct supply voltages (+15v for 7555's - +/-15v for Tl072)
- One pulser has 9.37v on it's output, while the other has 7.11v. They are on the same board, and share the TL072 for the necessary opamp.
- Looks like I have a solder bridge between the output and pins 2/4 on the last 7555 ("width"). That probably means something... 
Removed the solderbridge, then the output read 0v. Hooked the pulser up to the eg, fed a trigger into the pulser, got smoke. Now, the output read over 13v. Switched the power off and on again, and the output is back at 0v, so it seems to latch up when loaded.
Edit: Ah, nope it doesn't. It fluctuates between 13v and 0v.
Any clues in that?
C
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frijitz
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| Posted: Wed Aug 06, 2008 12:15 pm Post subject:
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| Coriolis wrote: | Removed the solderbridge, then the output read 0v. Hooked the pulser up to the eg, fed a trigger into the pulser, got smoke. Now, the output read over 13v. Switched the power off and on again, and the output is back at 0v, so it seems to latch up when loaded.
Edit: Ah, nope it doesn't. It fluctuates between 13v and 0v. |
If you have smoke, the chips are almost certainly destroyed. Your layout looks OK to me. So I'd say get a magnifier and check again for soldering issues and replace the chips.
Ian |
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Coriolis
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Coriolis
Joined: Apr 11, 2005
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Location: Stilling, Denmark
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| Posted: Wed Aug 06, 2008 12:48 pm Post subject:
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Hmm...with all the 7555's out, the opamp still in and power on, and no input - I have +15v on both opamp outputs!
That's not right, is it? Edit: Or maybe it is. Getting late here, turning in. Thanks for the help Ian...
C
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frijitz
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| Posted: Wed Aug 06, 2008 7:06 pm Post subject:
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| Coriolis wrote: | Hmm...with all the 7555's out, the opamp still in and power on, and no input - I have +15v on both opamp outputs!
That's not right, is it? Edit: Or maybe it is. |
Yes, it's right. The input comparator is normally high, as a negative-going pulse is needed to trigger the 555.
Ian |
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Coriolis
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| Posted: Thu Aug 07, 2008 4:41 am Post subject:
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After some sleep, I still can't see anything obviously wrong with the damn thing. Even checked the datasheet to see if there was anything to what you said about the possibility of a different pinout. Looks fine to me. Crap.
Will put this away for a while. Maybe I'll just buy a couple of boards when they come out...
C
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loss1234
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frijitz
Joined: May 04, 2007
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| Posted: Thu Aug 07, 2008 9:19 am Post subject:
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| Coriolis wrote: | After some sleep, I still can't see anything obviously wrong with the damn thing. Even checked the datasheet to see if there was anything to what you said about the possibility of a different pinout. Looks fine to me. Crap.
Will put this away for a while. Maybe I'll just buy a couple of boards when they come out... |
So did you replace the chips after fixing the soldering? I think the layout is OK.
Of course, we would be happy for you to buy some boards. 
Ian |
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Coriolis
Joined: Apr 11, 2005
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| Posted: Thu Aug 07, 2008 10:20 am Post subject:
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Well, yeah: Fixed the solderbridge - didn't help. Then removed the chips.
No cigar.
Well never mind.
I guess I would rather support the community and buy boards, than bang my head against the same wall for too long,
C
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epk
Joined: Apr 19, 2009
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Location: Sacramento, CA
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| Posted: Fri Jun 12, 2009 7:30 pm Post subject:
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I'm having a bit of trouble with the Delayed Pulser too! I'd happily get the aforementioned pcb, but I'm just driving a relay so the full EG is overkill and the Delayed Pulser portion does exactly what I need. (thanks Ian!)
For clarity's sake, here's what I'm referencing:
I'm running a TL082 and MC1455's on +/- 15v and if I isolate the opamp I think it's behaving correctly, providing +15v normally and flipping to -15v for the initial trigger duration. Pin 2 of the first 555 however doesn't seem to go low when the opamp does. I don't have access to an oscilloscope right now but I can usually see at least a fluctuation on my multimeter.
FWIW, when I adjust the pot on the first 555 there's no voltage output for the first 2/3 of the rotational distance then it very quickly goes high and it looks like hell is opening up inside the pot complete with smoke and fire!
Anyone got a clue for me?
tx
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frijitz
Joined: May 04, 2007
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| Posted: Fri Jun 12, 2009 8:59 pm Post subject:
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Two things. First, the pin 2 signal is a narrow pulse, so you won't see it on a multimeter. Second, the timers must be powered between ground and +15V. +/- 15 will fry them.
Thanks for your interest!
Ian |
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epk
Joined: Apr 19, 2009
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| Posted: Fri Jun 12, 2009 9:07 pm Post subject:
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| oh right, sorry, I DO have the timers powered by +15v and ground. Only the opamp is getting +/-15v. |
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frijitz
Joined: May 04, 2007
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| Posted: Sat Jun 13, 2009 7:20 am Post subject:
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You should add 1k resistors limiting in series with the 1M pots. My original circuit didn't need these, but with other pots it looks like the resistance gets low enough to cause excessive current into the timer chips.
The most recent documentation is posted on the Bridechamber site, and it includes the series resistors.
If you put your multimeter on pin 3 of the first timer chip you should be able to see the delay-time pulse (at the longest times).
Ian |
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epk
Joined: Apr 19, 2009
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| Posted: Sat Jun 13, 2009 8:00 pm Post subject:
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adding the 1k resistors to the pots took care of the fire
and after fixing some invisible solderbridges I got it working!
Thanks! |
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frijitz
Joined: May 04, 2007
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| Posted: Sat Jun 13, 2009 9:01 pm Post subject:
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| epk wrote: | adding the 1k resistors to the pots took care of the fire
and after fixing some invisible solderbridges I got it working! |
 Thanks for letting us know.
Ian |
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Coriolis
Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark
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| Posted: Sat Jun 13, 2009 11:46 pm Post subject:
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Yes, this is good to know!
I too was burning timers when I tried to build this on vero a long time ago... 
C
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