Search found 37 matches

by luix
21 Dec 2023, 20:36
Forum: DIY Projects
Topic: Low voltage tube overdrive
Replies: 12
Views: 2670

Re: Low voltage tube overdrive

If a triode is used as the second stage, the sound will be completely different and there will be much less overload. OK so the topology should be that depicted. I used a 7815 + 10V zener diode chip to filter the anode supply, to increase the filtering voltage, but several of these chips burned out...
by luix
21 Dec 2023, 17:50
Forum: DIY Projects
Topic: Low voltage tube overdrive
Replies: 12
Views: 2670

Re: Low voltage tube overdrive

Really nice sound! I don't know how did you recorded the samples but I can hear some noise, using high voltage tubes in space charge mode (low anode voltage) makes them more noisy. A solution I've tested with tube driver is to filter the anodic supply at least with a capacitance multiplier circuit, ...
by luix
31 Oct 2023, 19:58
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 22790

Re: Germanium and Silicon diodes comparison [documentation]

Usually the less sharp is the slope the softer is the clipping.

Give me some days and I'll use a scope to look at the sine clipping of MOS and zener.
by luix
31 Oct 2023, 10:25
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 22790

Re: Germanium and Silicon diodes comparison [documentation]

Perfect! thank you very much for satisfying my curiosity!!

So the MosDiode has a high Vth but with moderate slope, half way between silicon and germanium, it confirm my "hear" feeling :D
by luix
30 Oct 2023, 15:49
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 22790

Re: Germanium and Silicon diodes comparison [documentation]

Ciao! A mosfet connected in that way (D+G and S) is equivalent to two diode in antiparallel as below: MosDiode.jpg Using a multimeter (fluke 175) is possible to detect the two different Vth diode. Probably the Atlas is not able to detect the higher threshold diode due to the low working voltage, as ...
by luix
29 Oct 2023, 18:28
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 22790

Re: Germanium and Silicon diodes comparison [documentation]

Thank you very much! This is the body diode, the one that has anode on the source and catode on the drain, it is a sharp silicon diode. If you invert the connection of the alligator clip and connect the red one (anode) on the drain-gate and the black one on the source the diode will show the Vth of ...
by luix
28 Oct 2023, 16:50
Forum: DIY Projects
Topic: Germanium and Silicon diodes comparison [documentation]
Replies: 35
Views: 22790

Re: Germanium and Silicon diodes comparison [documentation]

Great work mate!!!

Can you also try to measure mosfet like BS170 in diode mode with Drain connected to Gate?

I've always used this configuration to have asymetrical clipping or soft clipping with a Vth of about 2V, I'm curious about the IV curve.
by luix
13 Jan 2023, 08:27
Forum: Pedal Debugging & Troubleshooting Support
Topic: AionFX L5 Preamp hates Chorus pedals. Rate LFO is audible and annoying
Replies: 4
Views: 536

Re: AionFX L5 Preamp hates Chorus pedals. Rate LFO is audible and annoying

To avoid this problem I usually supply the ticking oscillator with a capacitance multiplier filter, I don't know if this is a viable solution for your pedals. The kind of rectifier used in Aion preamp is the worst solution to power an fx, it's the same used in the tube driver and have the same noise...
by luix
03 Dec 2022, 12:48
Forum: DIY Projects
Topic: Bazz Me, Fuss You -- stop me if you think you've heard this one before [documentation]
Replies: 21
Views: 29752

Re: Bazz Me, Fuss You -- stop me if you think you've heard this one before [documentation]

You can also add a gain recovery stage like the big muff last stage.

Anyway nice fuzz and nice octave up.
by luix
07 Nov 2022, 16:30
Forum: DIY Projects
Topic: onboard buffer for BASS guitar (asking for advice) [documentation]
Replies: 23
Views: 3079

Re: onboard buffer for BASS guitar (asking for advice) [documentation]

The academic bias point for symetric and maximum output swing is half the supply voltage, so if you have 9V you should have 4.5V on the output of the buffer (the emitter in bootstrap case). Symulation says that wit 9V supply and the values above the emitter is sitting at 4.7V. CNBuffer_9V.PNG Charge...
by luix
07 Nov 2022, 13:28
Forum: DIY Projects
Topic: onboard buffer for BASS guitar (asking for advice) [documentation]
Replies: 23
Views: 3079

Re: onboard buffer for BASS guitar (asking for advice) [documentation]

a further question: will doubling the voltage just raise the headroom, like in OpAmps' case? I mean, will I have to change some resistors? thanks very much! Doubling the supply voltage will avoid clipping in case of hard slapping on the string. Probably the bias resistors should be adjusted but in ...
by luix
06 Nov 2022, 08:49
Forum: DIY Projects
Topic: onboard buffer for BASS guitar (asking for advice) [documentation]
Replies: 23
Views: 3079

Re: onboard buffer for BASS guitar (asking for advice) [documentation]

The more you beat your strings the more will be the signal level, I've measured humbucking guitar pickup with scope and the level goes to 2.5V peak for small time, since our hears are really sensible to any distortion my advice is to use the classic BJT bootstrapped buffer circuit (AKA Cornish) supp...
by luix
19 Jul 2022, 06:26
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Ic big muff Keeley psi vs original op amp thoughts
Replies: 4
Views: 587

Re: Ic big muff Keeley psi vs original op amp thoughts

Ah ok! 560k/62k combination has little less gain (10) and 0.26Hz highpass, 510k/47k combo has little higher gain (12) with 0.33Hz highpass, I think that a little less gain is preferably on fuzz circuit but it's a personal consideration. You should not worry about high pass frequency because the stag...
by luix
18 Jul 2022, 06:24
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Ic big muff Keeley psi vs original op amp thoughts
Replies: 4
Views: 587

Re: Ic big muff Keeley psi vs original op amp thoughts

I'm not sure it's a good idea, increasing 4 times the input cap of the second opamp will increase the bass responce of the circuit, @ max gain the pot shows 0 resistance to the second opamp so the 10k+1uF couple makes an highpass with fc 16Hz, 8.2k+4.7uF makes an highpass with fc 4Hz. I my experienc...
by luix
14 Jul 2022, 13:23
Forum: Pedal Debugging & Troubleshooting Support
Topic: 555 Voltage Doubler
Replies: 7
Views: 892

Re: 555 Voltage Doubler

I guess that class D power amp draws 20mA only without audio signal, with load you can brutally calculate the DC current required using the power formula P = I 2 *R load -> I = SQRT(P/R), for example to have 10W on 4ohm the DC current needed will be about 1.6A, stay safe increasing a bit that curren...
by luix
14 Jul 2022, 12:58
Forum: Davidoff Library
Topic: Audio Phaser, Electronics Today International, September 1976
Replies: 27
Views: 3711

Re: Audio Phaser, Electronics Today International, September 1976

Luix and Jose, both of your suggestions are great tidbits of information and good ideas worthy of mention. You're right, sorry! :oops: Long time ago I've experimented a lot with phasers and I found that using a CMOS inverter as variable resistor is really tricky so I've abandoned the design and I'v...
by luix
13 Jul 2022, 12:27
Forum: Pedal Debugging & Troubleshooting Support
Topic: 555 Voltage Doubler
Replies: 7
Views: 892

Re: 555 Voltage Doubler

MC34063 just add pi filter on the output. This is not a charge pump, it's a boost converter and it will work in discontinous mode for light load, so if the load don't draw 75mA constantly (as I've assumed, NE555 wont work well with all that current) it's not a good choice, even with CLC filter. The...
by luix
13 Jul 2022, 10:47
Forum: Davidoff Library
Topic: Audio Phaser, Electronics Today International, September 1976
Replies: 27
Views: 3711

Re: Audio Phaser, Electronics Today International, September 1976

In my experience that kind of LFO produce a current bump every time the waveform inverts and this bump is readily audible in output, to solve this problem I isolate the LFO opamp with a capacitance multiplier circuit, one transistor, one resistor and two or three capacitors 8)
by luix
13 Jul 2022, 07:26
Forum: Pedal Debugging & Troubleshooting Support
Topic: 555 Voltage Doubler
Replies: 7
Views: 892

Re: 555 Voltage Doubler

Let's use a dedicaded chip like the Microchip TC1044SCPA and ceramic 10uF capacitor, the expense would be a little bit higher but since you are not in an industrial production it will not be a finacial problem. Using a NE555 you will see the voltage rapidly drop down with load because of the high in...
by luix
18 Jun 2022, 10:40
Forum: Parts & Tools Sourcing & Trading
Topic: NOS transistor scam on eBay
Replies: 13
Views: 2594

Re: NOS transistor scam on eBay

It seems that '60s germanium transistors production was infinite!

Glass case transistors was the first ones that disappeared, leaving space to metal case ones, how is still possible to find them in such great quantity?? Where do they come from??