Search found 1969 matches

by mictester
23 Mar 2024, 22:05
Forum: Pedal Debugging & Troubleshooting Support
Topic: DownBox
Replies: 9
Views: 628

Re: DownBox

Just for the sake of experiment - try replacing D1 with a 560k - 1M resistor. You'll find that you will get much more sensitivity, and it may get rid of the unpleasant decay (somewhat).
by mictester
19 Mar 2024, 15:37
Forum: DIY Projects
Topic: A Single Chip Phaser!
Replies: 8
Views: 906

Re: A Single Chip Phaser!

More development of this basic design has gone on since. I felt that the effect was too mild, and it needed a couple of extra stages. To add these, I used another quad op-amp package. The extra two op-amps were used to extend the circuit a little - I added an output buffer (configured for unity gain...
by mictester
08 Mar 2024, 21:38
Forum: DIY Projects
Topic: A Single Chip Phaser!
Replies: 8
Views: 906

Re: A Single Chip Phaser!

The led indicator only works when phaser is off? No. When the "control input" to the gate of the FET is not connected, the LED lights, because the FET is biased on by the leakage through the upper diode. In the other switch position, the 100k pull-down resistor on the effect output is eno...
by mictester
08 Mar 2024, 21:33
Forum: DIY Projects
Topic: A Single Chip Phaser!
Replies: 8
Views: 906

Re: A Single Chip Phaser!

Dirk I've been "out of circulation" for some time, working on some real, paying design projects for an American company. In the meantime, I've retired, moved out of the big city, and taken up rural life again. I really don't care what you think of me - making assumptions before actually me...
by mictester
05 Mar 2024, 00:56
Forum: DIY Projects
Topic: A Single Chip Phaser!
Replies: 8
Views: 906

A Single Chip Phaser!

I found my original, 1970s one-of-a-kind little homemade phaser when I was rummaging around for some leads the other night. There were two prototypes built of this one - the first one with a pair of 4558s and the second using a RC4136 quad op-amp. There were three more made (since they worked pretty...
by mictester
06 Aug 2023, 02:22
Forum: DIY Projects
Topic: 21st Century Big Muff [documentation]
Replies: 39
Views: 24695

Re: 21st Century Big Muff [documentation]

After making quite a few of these, I had two returns that turned out to have fried input op-amp stage. Adding the two LEDs as shown in this diagram protects the input successfully. You don't have to use LEDs - you could use two pairs of 1N4148s in series in this position which would work just as wel...
by mictester
05 Aug 2023, 01:05
Forum: Davidoff Library
Topic: Waa Waa Pedal, Hobby Electronics, November 1978 🇬🇧
Replies: 3
Views: 2093

Re: Waa Waa Pedal, Hobby Electronics, November 1978

jrod wrote: 31 Jul 2023, 17:28 It looks like there is correction on the schematic. So, does one terminal of RV1 go to ground?
No. It's just used as a variable resistor.
by mictester
09 Jul 2023, 00:53
Forum: Pedal Debugging & Troubleshooting Support
Topic: Help With Fuzz Face Circuit
Replies: 2
Views: 436

Re: Help With Fuzz Face Circuit

Why waste your time with these notoriously unreliable breadboards? It's certainly quicker and easier to just solder the circuit together on a piece of stripboard, especially as the Fuzz Face circuit uses just two transistors, four resistors, three capacitors and two pots. Word of advice - you'll fin...
by mictester
02 Jul 2023, 22:30
Forum: DIY Projects
Topic: "That" compressor - good, easy, adjustable DIY compressor [documentation]
Replies: 7
Views: 2199

Re: "That" compressor - good, easy, adjustable DIY compressor [documentation]

That is a pretty nifty piece of design, and you've made a very good job of explaining your design approach and reasoning. I have one (minor) criticism: I've never liked "exposing" Op-Amp inputs directly to the Outside World ™ - I've always found them to be somewhat vulnerable - so I'd be i...
by mictester
12 Jun 2023, 23:30
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Budda - Chakra Compressor [schematic]
Replies: 11
Views: 7733

Re: Budda Chakra Compressor [schematic]

Not to throw water on this design, but... If you want an opto compressor sound, this ISN'T the circuit to copy. You're exactly right! My simple compressor uses the LDR in the negative feedback loop around an op-amp for exactly the reasons you outline in your post. Incidentally, I've recently found ...
by mictester
02 Jun 2023, 01:22
Forum: Davidoff Library
Topic: Q.A. Rice, Guitar Note Expander, Electronics Today International, April 1981 🇦🇺
Replies: 15
Views: 4219

Re: Q.A. Rice, Guitar Note Expander, Electronics Today International, April 1981 🇦🇺

The finished versions of this circuit I've built lately have had additional transistor buffers on the way in and the way out. The 4007 is quite a sensitive beast, and easily killed by large voltage spikes. The transistor buffers ("emitter followers") completely eliminate the problems at ve...
by mictester
30 May 2023, 00:00
Forum: Davidoff Library
Topic: Q.A. Rice, Guitar Note Expander, Electronics Today International, April 1981 🇦🇺
Replies: 15
Views: 4219

Re: Q.A. Rice, Guitar Note Expander, Electronics Today International, April 1981 🇦🇺

Just stumbled across this thread. I remember the author of the article above - Quentin Rice worked in the same place as me at the time! My take on the circuit (which really wasn't all Quentin's work) was a simplified version without the rotary switch, but with two DPDT footswitches: Effect / Bypass ...
by mictester
29 May 2023, 12:52
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Caline CP-29 White Heat [schematic]
Replies: 31
Views: 8750

Re: Caline CP-29 White Heat [schematic]

For input/output buffers, using another TL072 sounds like a good choice. It provides better impedance for your guitar compared to discrete transistors without a bootstrapped configuration. Plus, using the TL072 means fewer parts, which is always convenient. I'm with you on the original narrow box T...
by mictester
29 May 2023, 12:44
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Caline CP-29 White Heat [schematic]
Replies: 31
Views: 8750

Re: Caline White Heat gut shots [schematic]

They did that to reduce PSU noise. ok, but how? I don't understand the purpose of adapting the impedance, a buffer doesn't reduce hum by itself as far as I know If the half rail is sourced from an op-amp (as here) the capacitor from the non-inverting input to ground is made much more effective, lea...
by mictester
22 May 2023, 00:38
Forum: Modern Stompbox Effects (1975 - ...)
Topic: MOOG Moogerfooger MF-103 12-Stage Phaser [schematic]
Replies: 85
Views: 61142

Re: MOOG Moogerfooger MF-103 12-Stage Phaser [schematic]

There is a fundamental design flaw with this circuit - the LM13600 / 13700 is both noisy and distorted. Put a few of them after one another, and the problems will be multiplied!
by mictester
22 May 2023, 00:28
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Electro Harmonix Bass Big Muff [schematic]
Replies: 15
Views: 9771

Re: Electro Harmonix Bass Big Muff [schematic] [schematic]

Hi pals, Something that intrigues me is why EH continues to use the 4 transistors in TO92 format, even though the other components have been migrated to SMD :scratch: Why not also use the SMD version of the BC547 ? Cheers, Jose That will be because EHX bought a few million BC547 for less than $0.00...
by mictester
21 May 2023, 19:03
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Caline CP-29 White Heat [schematic]
Replies: 31
Views: 8750

Re: Caline White Heat gut shots [schematic]

They did that to reduce PSU noise. ok, but how? I don't understand the purpose of adapting the impedance, a buffer doesn't reduce hum by itself as far as I know Look at the electrolytic capacitors - one (effectively) across the 9V supply, and another at the voltage reference point for the ½V rail. ...
by mictester
02 May 2023, 20:17
Forum: Vintage Stompbox Corner ( ... - 1975)
Topic: Dharma Sound Sweeper???
Replies: 1
Views: 817

Re: Dharma Sound Sweeper???

It's an envelope controlled AutoWah. Not very good as I remember
by mictester
20 Feb 2023, 21:22
Forum: Davidoff Library
Topic: Anthony Leo, Treble Boost & Preamplifier For Your Guitar, Electronics Australia, February 1969 🇦🇺
Replies: 1
Views: 1840

Re: Anthony Leo, Treble Boost & Preamplifier For Your Guitar, Electronics Australia, February 1969

This is almost exactly the same circuit that I built - in 1969 - as my very first ever guitar effect! It got built inside the control cavity of my Burns guitar, and I replaced the original tone pot with one with a push/pull switch action to engage the booster! My Dad and I worked out the circuit we ...
by mictester
08 Jan 2023, 11:49
Forum: Davidoff Library
Topic: Anthony Leo, A Fuzz Box for Electric Guitar, Electronics Australia, August 1967 🇦🇺
Replies: 7
Views: 1754

Re: Anthony Leo, A Fuzz Box for Electric Guitar, Electronics Australia, August 1967 🇦🇺

It's actually a very good fuzz box with buffering! The only (minor) problem is that you can get a "pop" when switching off. I updated it a few years later with switching done with a 4066 CMOS switch, which completely eliminated the switching noise. I also used the usual stereo input jack t...