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2010-11-16 by Tom Wiltshire
I'd like to add a bit on various points; I used to build a lot of stompboxes, and I often used op-amps. I mainly used to use the TL062/064 since it has a lower current draw than the TL072/074, which extends the useful battery life. LF444 was another low current op-amp I remember
2010-11-15 by nn3nn3
The problem with dividing the supply voltage is the opamp headroom. Whether you use a LM1458 or TL072, the output voltage swing can be as bad as 3V less than the supply (but usually it's only 1-1.5V less). So with +/-4.5V supply you could be down to +/-1.5V headroom on the output
2010-11-13 by Dave Kendall
Thanks Ken. I have a spare CGS30 board already built, and I'm putting it in a temporary housing ready for tomorrow's rehearsal/tryout. I'll add the second capacitor, and probably a 2.1mm DC input jack as well if it'll drink juice - my mate has a DC supply in his pedal board. I bo
2010-11-13 by sasami@hotkey.net.au
>As noise levels are not critical for his intended use, for power, I >guess I could use a resistor divider with a 9V battery to, generate >±4.5V, with the centre tap to GND on the PCB, and something like a 47uF >cap between the centre tap and 0V on the battery (which is now -4.5V
2010-11-13 by Dave Kendall
Hi Jason. The CGS46 is indeed a neat circuit, but the modded board needs to run from a 0V to 9V DC supply. (that's an easy mod), and it will be in a tiny enclosure along with a few other bits and bobs, so I was hoping to find a way to tweak the circuit itself to have some sort of
2010-11-13 by Jason Proctor
could just use the CGS stompbox adapter :-) http://www.cgs.synth.net/modules/cgs46_sba.html >Hi all. > >Mad idea I know, but it's a request from a guitarist mate. > >As noise levels are not critical for his intended use, for power, I >guess I could use a resistor divider with a 9
2010-11-13 by Dave Kendall
Hi all. Mad idea I know, but it's a request from a guitarist mate. As noise levels are not critical for his intended use, for power, I guess I could use a resistor divider with a 9V battery to, generate ±4.5V, with the centre tap to GND on the PCB, and something like a 47uF cap b
2010-11-10 by Pete
No, but I should give it a try. pete On Tue, Nov 9, 2010 at 10:25 PM, sasami@... > wrote: > > > Have you tried linear pots instead of the log pots? > > Ken > > > >I built two CGS-VCS, and they both have the same issue of pot range. The > >pots are also very sensitive at the high
2010-11-10 by sasami@hotkey.net.au
Have you tried linear pots instead of the log pots? Ken >I built two CGS-VCS, and they both have the same issue of pot range. The >pots are also very sensitive at the high end. This is not a very accurate >module, but it is very useful. I use it mostly like an envelope, and it >w
2010-11-10 by Pete
I built two CGS-VCS, and they both have the same issue of pot range. The pots are also very sensitive at the high end. This is not a very accurate module, but it is very useful. I use it mostly like an envelope, and it works great! Check it out in this vid I made. I am mostly pla
2010-11-10 by sirolffoonav
dear, i'm looking for build & tested cgs pcb's and modules. almost any of them but asr, steiner vcf and psycho lfo are already in my system. no problem if there are still pots & sockets to wire, but after that the module should be working. other diy modules and pomona banana cabl
2010-11-09 by russma04
Thanks very much Steve. Indeed I *had* heard about the pot quirky-ness from someone on Muff's, (possibly you!) But, I decided to try another set of pots anyway, based on another user reportedly fixing this symptom by replacing the pots. Anyway, I didn't have a specific purpose in
2010-11-09 by Steve
Hi Russ - Are you sure the pots aren't doing "anything" for 3/4 of their travel? These units are noted for their quirkiness and touchiness of the pots settings. And a lot depends on what you're using it for. For LFO and envelope use, yes, on my units (with log pots) I only use ab
2010-11-09 by sasami@hotkey.net.au
>Thanks Ken. I checked the resistor, and it's 22K. The cap is marked as 22nK63, but when I check it with the meter, it reads 37n. Seems wrong, no? Close enough. There are other capacitances coming into play. >Also, the replacement pots I used are 10K audio taper. Try linear pots
2010-11-09 by russma04
Thanks Ken. I checked the resistor, and it's 22K. The cap is marked as 22nK63, but when I check it with the meter, it reads 37n. Seems wrong, no? Also, the replacement pots I used are 10K audio taper. --- In cgs_synth@yahoogroups.com , sasami@... wrote: > > Short of you having th
2010-11-09 by sasami@hotkey.net.au
You said you replaced the pots - did you use linear pots? What value? Ken >So I replaced the two Rate pots and still have the same problem, which is that the Rate pots don't start to do anything until 3/4 of the way through the turn. I'm not a troubleshooting wiz, so I could use
2010-11-09 by sasami@hotkey.net.au
Short of you having the wrong part installed, somewhere, I'm not sure what the problem would be. Connected the bases of the four transistors is a resistor. Should be 22k or even 18k. Th capacitor across the op anp should be 22n. If is possible it may be a 2n2 if you have one of t
2010-11-08 by russma04
So I replaced the two Rate pots and still have the same problem, which is that the Rate pots don't start to do anything until 3/4 of the way through the turn. I'm not a troubleshooting wiz, so I could use some direction. Between these pots and the output are the pairs of 3904/390
2010-11-07 by spiralsect
Thank you Ken. Cheers, Adam-V --- In cgs_synth@yahoogroups.com , sasami@... wrote: > > These days I would use 15k there, but the reality is in this particular > circuit it really doesn't matter if it's 22k or 2k2 because the Comp Sense > control compensates for it. My prototype w
2010-11-07 by sasami@hotkey.net.au
These days I would use 15k there, but the reality is in this particular circuit it really doesn't matter if it's 22k or 2k2 because the Comp Sense control compensates for it. My prototype would have had 2k2 in it because I would have followed what is marked on the overlay. Ken >H
2010-11-07 by spiralsect
Hi, Can somebody please confirm for me that the resistor next to the LM358 at the top of the board should actually be a 22k as shown on the schematic, not a 2k2 as printed on the board? It's a Rev 2.0 board. Thanks Adam-V.
2010-11-05 by david rickert
www.pillsrxus.com [Non-text portions of this message have been removed]
2010-10-30 by sasami@hotkey.net.au
>I'm still working on mine. The rise and fall rate pots don't have any effect until 3/4 of the way through the range. I know they are log. pots, but that doesn't seem right? No, that doesn't seem right! Ken > > >--- In cgs_synth@yahoogroups.com , liam cloyd wrote: >> >> glad you
2010-10-30 by russma04
That's right, but I was referring to the rate pots. --- In cgs_synth@yahoogroups.com , "Guy" wrote: > > The Rise & Fall pots must be linear (50k). > > _g > > > --- In cgs_synth@yahoogroups.com , "russma04" wrote: > > > > I'd like to do that Liam, but the camera-to-computer cable
2010-10-30 by Guy
The Rise & Fall pots must be linear (50k). _g --- In cgs_synth@yahoogroups.com , "russma04" wrote: > > I'd like to do that Liam, but the camera-to-computer cable I'd need is in storage, (I'm living in temporary housing right now, and most of my stuff is in storage). If I can grab
2010-10-30 by russma04
I'd like to do that Liam, but the camera-to-computer cable I'd need is in storage, (I'm living in temporary housing right now, and most of my stuff is in storage). If I can grab a cable somewhere, I'll post some up. In the meantime, if you're at all unsure during your build feel
2010-10-30 by liam cloyd
glad you are making progress! any way you could post some close up pics on muffs so i can see the orientation and parts etc. [Non-text portions of this message have been removed]
2010-10-29 by Richard Brewster
This problem boils down to a reversed power connector. Not from plugging in backwards, but from the connector being in backwards. Worst case some chips may be blown. If they are in sockets, easy to swap. Let us know what happened. Richard http://pugix.com On 10/29/10 1:51 PM, Ove
2010-10-29 by Ove Ridé
That's not good for either the power supply or the module. The power supply might take damage from the overload (although good linear regulators should have various shutdown mechanisms.) It's also not good for the module since transistors (including those in ICs) have a tendency
2010-10-29 by russma04
Wow. That you so much for all your help folks. I did indeed have the MOTM power header installed backwards. So I re-installed it correctly and it no longer pulls down the Q960, and the pins measure +/-15v. I haven't had time yet to test all the other functions, I just wanted to g
2010-10-29 by Todd
Maybe double check the wiring. You might be shorting out through a miswired pot. -TF --- In cgs_synth@yahoogroups.com , "russma04" wrote: > > When I plug in the VCS and measure the power pins from the bottom of the PCB, I don't get + and - 15v, I get much smaller amounts. > > Als
2010-10-29 by Richard Brewster
Very good point. The CGS75 board has the orientation of the 4-pin MOTM MTA header facing IN, so that if you use a standard MOTM power cable, the wires exit on the inside, going back over the board components. This is the reverse of MOTM boards. Richard Brewster http://www.pugix.c
2010-10-29 by Ove Ridé
Is the power header correctly mounted to the board and connected? On 29 October 2010 01:34, russma04 russm@... > wrote: > > > > Thanks Richard and Ken. Unplugged power pin resistance measures 5K and 58K. No backwards chips. What else would cause the excessive load? > > --- In cgs
2010-10-29 by sasami@hotkey.net.au
>Thanks Richard and Ken. Unplugged power pin resistance measures 5K and 58K. No backwards chips. What else would cause the excessive load? Measure both directions incase you have a diode effect happening (i.e. the load is only in one direction). A wiring error - such as one of th
2010-10-28 by russma04
Thanks Richard and Ken. Unplugged power pin resistance measures 5K and 58K. No backwards chips. What else would cause the excessive load? --- In cgs_synth@yahoogroups.com , sasami@... wrote: > > Backwards chip? > > It sounds like your PSU is going into current limit/shutdown when
2010-10-28 by sasami@hotkey.net.au
Backwards chip? It sounds like your PSU is going into current limit/shutdown when switched on, due to the excessive load. Ken >When I plug in the VCS and measure the power pins from the bottom of the PCB, I don't get + and - 15v, I get much smaller amounts. > >Also, when the VCS
2010-10-28 by Richard Brewster
With power unplugged, measure the resistance from +15 pin to ground and -15 pin to ground. Mine are 5K (+15) and 350K (-15). Yours should be similar or something is amiss. Richard Brewster http://pugix.com On 10/28/10 2:19 PM, russma04 wrote: > When I plug in the VCS and measure
2010-10-28 by russma04
When I plug in the VCS and measure the power pins from the bottom of the PCB, I don't get + and - 15v, I get much smaller amounts. Also, when the VCS is plugged in, my dotcom Q960 doesn't work at all. No smoke, nothing seems to be getting hot. Any ideas? Thanks
2010-10-27 by cg_synth
--- In cgs_synth@yahoogroups.com , "russma04" wrote: > > The silkscreen on my CGS75 PCB has a 2N3904 for the LED driver transistor, instead of the BC547. Can I assume the orientation is silkscreened correct for that transistor, or do I need to install it backwards to match the BC
2010-10-27 by russma04
The silkscreen on my CGS75 PCB has a 2N3904 for the LED driver transistor, instead of the BC547. Can I assume the orientation is silkscreened correct for that transistor, or do I need to install it backwards to match the BC547 pinout?
2010-09-30 by spiralsect
Hi, I'm looking to build the Serge 1973 VCF and the VCS but cannot get 20k pots in the format that I require. I can get 10k or 50k. Would using a 50k pot in the CV processing sections cause any undue grief? If so, would the simplest solution be to use a dual 50k wired in parallel
2010-09-13 by sasami@hotkey.net.au
Thanks for the alert. I'd probably try LM3140 next, but get a few spare so you can swap out any that have an offest. Fortunately, most of the ones I have had have had the same offset, with only the occasional bad one. I assume you are referring to Greencaps. I just used a version
2010-09-13 by Doug
I just finished my ASR and thought I'd share my experience. Turns out the National LF356's I used were probably bootleg. They performed TERRIBLY. I temporarily replaced them with TL071's with OK results - nothing fantastic, but at least they hold fairly well for a second or so. I
2010-09-12 by spiralsect
Hi Chris, There are times when you just need to amplify a sigle a little in order to use it more effectively. For example, blacet VCAs don't fully open with doepfer enveope generators, so something that can amplifiy the envelopes a little would be rather useful. With enough gain,
2010-09-12 by Mr Waverly
Adam, Would you mind saying why you thought you needed more than the standard gain? What were the values you settled on? Haven't built mine yet and may follow your lead. Regards Chris H Sent from my iPhone On Sep 12, 2010, at 5:08 AM, "spiralsect" adam-v@... > wrote: > Increasing
2010-09-12 by spiralsect
Increasing the feedback resistor in the second op-amp works a treat; thanks Ken. Cheers, Adam. --- In cgs_synth@yahoogroups.com , "spiralsect" wrote: > > Thanks Ken, looks like some experimentation is in order. I'll breadboard the circuit and try your suggestions before I commit
2010-09-12 by spiralsect
Thanks Ken, looks like some experimentation is in order. I'll breadboard the circuit and try your suggestions before I commit any sort of gain control to my panel design. Cheers, Adam. --- In cgs_synth@yahoogroups.com , sasami@... wrote: > > Not tried either but suggestions are :
2010-09-11 by sasami@hotkey.net.au
Not tried either but suggestions are : decrease the value of the input resistor, or increase the value of the second feedback resistor only. Ken >Hi, > >I'm looking at building CGS75 Voltage Controlled Slope and was wondering if it was possible to increase the gain of the process
2010-09-11 by spiralsect
Hi, I'm looking at building CGS75 Voltage Controlled Slope and was wondering if it was possible to increase the gain of the processor stage. My op-amp theory is very rusty but I was thinking that, provided the values are kept in proportion, I could just increase the value of the
2010-09-04 by Rico Loverde
Thank you guys, I really appreciate the help. Gonna try the buffer route tomorrow. The expander sounds like a great idea, thanx Laurie. On Fri, Sep 3, 2010 at 10:11 PM, Elby Designs elby_designs@... >wrote: > > > The point marked Mixer Bus is a virtual ground so you won't see any