Search found 1695 matches

by Manfred
20 Feb 2024, 20:00
Forum: Pedal Debugging & Troubleshooting Support
Topic: Dunlop Cry baby JH-1 low headroom [SOLVED]
Replies: 8
Views: 650

Re: Dunlop Cry baby JH-1 low headroom [SOLVED]

You have replaced both transistors with 2N5088 types. That was wrong, because according to the original circuit diagram, the first transistor is an MPSA13, which is a Darlington transistor. I have made another circuit simulation to see more precisely. The clipping of the sinusoidal signal always occ...
by Manfred
20 Feb 2024, 12:54
Forum: Pedal Debugging & Troubleshooting Support
Topic: Dunlop Cry baby JH-1 low headroom [SOLVED]
Replies: 8
Views: 650

Re: Dunlop Cry baby JH-1 low headroom [SOLVED]

I ran a circuit simulation and found that the shape of the output signal started to round off at about 1.3 Vpeak.
This happens at certain frequencies depending on the potentiometer setting.
Does your guitar have a pickup with a high output level?
by Manfred
11 Feb 2024, 10:40
Forum: Pedal Debugging & Troubleshooting Support
Topic: Boss PH1r
Replies: 4
Views: 447

Re: Boss PH1r

Connect drain-source from Q6 and see if the phaser signal then comes out.
by Manfred
09 Feb 2024, 22:56
Forum: DIY Projects
Topic: OGBip-2 overdrive on 2n5088 bipolar transistor
Replies: 11
Views: 707

Re: OGBip-2 overdrive on 2n5088 bipolar transistor

Thanks for sharing, I like the sounds. :thumbsup
by Manfred
22 Jan 2024, 19:00
Forum: Pedal Debugging & Troubleshooting Support
Topic: charge pump voltage divider issues?
Replies: 5
Views: 586

Re: charge pump voltage divider issues?

Insert a 7809 voltage regulator with the usual parts around between the plug-in power supply connection and your circuit.
by Manfred
18 Jan 2024, 21:34
Forum: Pedal Debugging & Troubleshooting Support
Topic: Rat - high pitched squeal
Replies: 4
Views: 597

Re: Rat - high pitched squeal

Some op-amps tend to oscillate with a larger capacitive load.
Try the in-loop compensation from this article.
https://www.analog.com/en/analog-dialog ... er-25.html
by Manfred
07 Jan 2024, 11:29
Forum: Amplifiers
Topic: Fender H.O.T. practice amp hum (50hz) noise even the guitar is un plugged.
Replies: 20
Views: 2910

Re: Fender H.O.T. practice amp hum (50hz) noise even the guitar is un plugged.

Thank you George for your hints, I will try this out on the next amplifier with a hum problem.
Peavey Bandit Detail.jpg
by Manfred
06 Jan 2024, 21:21
Forum: PCB Guitar Mania - pedal builders group and debug
Topic: Maximum Crank no effect sound
Replies: 9
Views: 1762

Re: Maximum Crank no effect sound

Is the 3PDT switch soldered in twisted?
by Manfred
30 Nov 2023, 16:29
Forum: DIY Projects
Topic: Tetrafuzz
Replies: 7
Views: 3167

Re: Tetrafuzz

Great development, sounds good to me ! :thumbsup
by Manfred
23 Nov 2023, 22:17
Forum: Parts & Tools Sourcing & Trading
Topic: *best* LDR for Mutron III / Neutron circuit
Replies: 40
Views: 27175

Re: *best* LDR for Mutron III / Neutron circuit

I assume that by omitting the first two letters before 1558 in the schematic, Musitronics had the option to install the Omp amps depending on market availability.
There were LM1558, MC1558, CA1558 and perhaps other designators.
by Manfred
23 Nov 2023, 09:04
Forum: Parts & Tools Sourcing & Trading
Topic: *best* LDR for Mutron III / Neutron circuit
Replies: 40
Views: 27175

Re: *best* LDR for Mutron III / Neutron circuit

In the factory schematic, all OP amps are specified as 1558. The Mutron on my bench shows two RC4558BP and one RC4558BN. Since the device works, I leave this in its original state so as not to reduce the value. Yes, in some modifications the lower noise NE5532 are recommended for the signal path to ...
by Manfred
20 Nov 2023, 22:43
Forum: Parts & Tools Sourcing & Trading
Topic: *best* LDR for Mutron III / Neutron circuit
Replies: 40
Views: 27175

Re: *best* LDR for Mutron III / Neutron circuit

I created this Mutron III PCB clone for troubleshooting. I took the component identifiers and the values from the factory circuit diagram. It was an unexpected fault, part of a trace under A5&A5 was oxidized away. Probably battery acid from a leaking battery, there was also a small oxidized area...
by Manfred
16 Nov 2023, 21:36
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Mooer - Grey Faze / Tomsline - G-fuzz
Replies: 9
Views: 2709

Re: Mooer - Grey Faze / Tomsline - G-fuzz

Hi Bernardduur.
thanks for reading the voltage values. :thumbsup
by Manfred
11 Nov 2023, 23:29
Forum: Pedal Debugging & Troubleshooting Support
Topic: really bad RFI. What are some good tricks for eliminating radio frequency interference?
Replies: 3
Views: 747

Re: really bad RFI. What are some good tricks for eliminating radio frequency interference?

I do not know the circuit, but I would say that the 100pF capacitor shorts the radio frequency to ground. The 68pF capacitor between collector and base multiplied by the step gain appears as a so-called Miller capacitance at the base which is in parallel to the 100pF capacitor. This means that the c...
by Manfred
04 Nov 2023, 10:19
Forum: Amplifiers
Topic: Fender H.O.T. practice amp hum (50hz) noise even the guitar is un plugged.
Replies: 20
Views: 2910

Re: Fender H.O.T. practice amp hum (50hz) noise even the guitar is un plugged.

Rewired the ground loop breaker circuit, now the wiring is correct according to the wiring diagram.
The circuit works fine, the hum is gone.
hum loop breaker wiring  corrected.jpg
by Manfred
04 Nov 2023, 09:28
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Mooer - Grey Faze / Tomsline - G-fuzz
Replies: 9
Views: 2709

Re: Mooer - Grey Faze / Tomsline - G-fuzz

Thanks for sharing.
Can you please measure the following voltage values.
At the base of Q1.
At the emitter of Q2
At the connection point between R4 and R7.
by Manfred
03 Nov 2023, 10:27
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 20927

Re: Germanium and Silicon diodes comparison [documentation]

I traced the curves of 20 KINGBRIGHT L4531D red diffused LEDs. This LED is of the GaAsP/GaPn 617nm type and has a nicely rounded curve. This is the same for all LEDs of this type and independent of the housing shape and diameter. I have not found the L4531D anymore, there are others in the Kingbrigh...
by Manfred
02 Nov 2023, 13:54
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 20927

Re: Germanium and Silicon diodes comparison [documentation]

1N60P 1N60 Comparatiob.jpg
1N60 versus 1N60p graph data:
1N60P-1N60 Comparation.txt
(2.83 KiB) Downloaded 62 times
by Manfred
01 Nov 2023, 23:07
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 20927

Re: Germanium and Silicon diodes comparison [documentation]

I traced the B-E junctios from 20 MPSA 18 NPN-transistors.
There were two groups of curves that are very similar, probably the 20 pieces come from two different productions.
MPSA18 B-E.jpg
MPSA18 DCA 75 graph data:
MPSA18 B_E.txt
(25.6 KiB) Downloaded 60 times