Search found 527 matches

by jorg
Wed Apr 08, 2020 2:40 pm
Forum: Music Tech DIY
Topic: compressor transformer
Replies: 3
Views: 61

Re: compressor transformer

Why does your compressor need a transformer?
by jorg
Wed Apr 08, 2020 2:39 pm
Forum: Music Tech DIY
Topic: Belton brick to spring tank MOD
Replies: 5
Views: 44

Re: Belton brick to spring tank MOD

I don't imagine there's much similarity between a DSP brick and a physical spring. I drive my springs with a small speaker amp, though a series resistor (5x the nominal DC resistance of the input coil) - that gives a brighter response. On the output side, a low-noise high input impedance preamp, gai...
by jorg
Wed Apr 08, 2020 10:19 am
Forum: Eurorack Modules
Topic: Eurorack Pitch Quantizer Comparison
Replies: 65
Views: 2505

Re: Eurorack Pitch Quantizer Comparison

My A-156 outputs tuning within a couple of cents over several octaves (haven't formally tested how much of that is actually related to VCO accuracy). I am surprised to hear it's 8 bits; they must be very accurate bits (i.e. 8-bit resolution but greater than 8-bit linearity and repeatability).
by jorg
Wed Apr 08, 2020 9:06 am
Forum: Music Tech DIY
Topic: dry/wet cv control
Replies: 3
Views: 100

Re: dry/wet cv control

Music thing modular's spring reverb schematic has a v simple vactrol wet/dry mix. You don't actually need two VCAs, you can do it with one VCA: say u have W for wet and D for dry, you put W-D through a VCA and mix the output with D. That way when the VCA is closed, you get (W-D)*0+D = D, ie fully d...
by jorg
Tue Apr 07, 2020 2:09 pm
Forum: Eurorack Modules
Topic: warmest sounding complex oscillator?
Replies: 68
Views: 3073

Re: warmest sounding complex oscillator?

AJH Entropic Doom? It's a noisillator, not just a drop-in replacement for your basic saw/square/sine. It has a lot of warmth and character.
by jorg
Sat Apr 04, 2020 12:48 pm
Forum: Music Tech DIY
Topic: Diodes at Header... Best Practices?
Replies: 29
Views: 518

Re: Diodes at Header... Best Practices?

Generally I use series Schottkys at the power inputs. I don't know what configuration you are looking at.
Euro Power Diodes.PNG
by jorg
Sat Apr 04, 2020 12:31 pm
Forum: Music Tech DIY
Topic: Filter Design Theory
Replies: 10
Views: 261

Re: Filter Design Theory

Analog Devices Linear Circuit Design Handbook is amazing; chapter 8 on filters is indispensable.
https://www.analog.com/en/education/edu ... dbook.html#
https://www.analog.com/media/en/trainin ... apter8.pdf
by jorg
Sat Apr 04, 2020 12:18 pm
Forum: Music Tech DIY
Topic: Variable signal routing.
Replies: 2
Views: 70

Re: Variable signal routing.

I don't see how you are detecting AC. There's no capacitor in the signal path.

It looks like you want to allow a signal through unless it exceeds a certain DC threshold; this is a bit different than sorting AC from DC.
by jorg
Fri Apr 03, 2020 10:55 am
Forum: Music Tech DIY
Topic: Film caps vs MLCC caps?
Replies: 21
Views: 517

Re: Film caps vs MLCC caps?

Somewhere I read that if you use a higher voltage MLCC cap than needed it would reduce microphonics but I can't find it. This was for SMD caps too. It was an app note from Kemit, Panasonic or someone else that makes caps. Basically let's say you put it in a 15V circuit, a 25V part would work but if...
by jorg
Fri Apr 03, 2020 10:33 am
Forum: Music Tech DIY
Topic: Muting 12 channels efficiently
Replies: 7
Views: 144

Re: Muting 12 channels efficiently

That 2-JFET circuit looks pretty reasonable to me. Simple, cheap, and clean. You could make R3 a pot to adjust the muting time.
by jorg
Fri Apr 03, 2020 10:25 am
Forum: Music Tech DIY
Topic: Trigger/Gate Time!
Replies: 26
Views: 348

Re: Trigger/Gate Time!

If you are going to do it in software that is overkill. ... The simplest is three transistors: I'm a bit startled to see a one-shot requiring software. I agree with Graham; this is a job for a few transistors, not a software development system. If I needed a one-shot inside a much larger applicatio...
by jorg
Fri Apr 03, 2020 10:08 am
Forum: Modular Synth General Discussion
Topic: Social Distancing Modular Synth Bingo
Replies: 26
Views: 810

Re: Social Distancing Modular Synth Bingo

I literally leave my modular blinking away in my bedroom as a night light. Often (e.g. last night) I leave the speakers on with a generative patch running. It gives me vivid dreams.
by jorg
Fri Apr 03, 2020 9:52 am
Forum: Music Tech DIY
Topic: Lab-Synth
Replies: 23
Views: 684

Re: Lab-Synth

Very good results!
by jorg
Fri Apr 03, 2020 9:50 am
Forum: Music Tech DIY
Topic: Transistor identification help
Replies: 3
Views: 57

Re: Transistor identification help

The matched-pair equivalents are BCM847 and BCM857. They're surface-mount, but you can easily get an adapter and use it to add through-hole leads. The "BS" package is "6TSSOP" or "TSSOP-6" or "SOT363-6" (all three terms are synonymous). https://www.digikey.com/products/en?keywords=bcm847bs https://w...
by jorg
Fri Apr 03, 2020 8:19 am
Forum: Music Tech DIY
Topic: Gould OS 250 10MHz scope
Replies: 9
Views: 396

Re: Gould OS 250 10MHz scope

florenceccollinsc wrote:
Fri Apr 03, 2020 6:14 am
SainSmart DSO212 a terrific little tool for testing small electronics on the go.
I looked at Sainsmart's site - they've got several nice-looking models.
by jorg
Thu Apr 02, 2020 1:11 pm
Forum: Music Tech DIY
Topic: Film caps vs MLCC caps?
Replies: 21
Views: 517

Re: Film caps vs MLCC caps?

Yes, if the capacitor is connected to the power pin of an IC, and the other end goes to ground, it's used for decoupling the power; MLCC is OK there. Audio signal path capacitors might be for filtering, or integrator in an oscillator, or blocking DC between stages of an audio circuit. MLCC would be ...
by jorg
Wed Apr 01, 2020 1:58 pm
Forum: Music Tech DIY
Topic: Film caps vs MLCC caps?
Replies: 21
Views: 517

Re: Film caps vs MLCC caps?

When using MLCC capacitors in the signal path, make sure they are C0G type. Other ceramic materials like X7R, X5R and Y5V reduces the capacitance when a dc bias voltage is applied, sometimes drastically. I second that point, and the microphonics. Any ceramic cap in the audio path should be C0G; oth...
by jorg
Tue Mar 31, 2020 7:14 am
Forum: Music Tech DIY
Topic: CD4024 Reset (Clock Debug)
Replies: 7
Views: 139

Re: CD4024 Reset (Clock Debug)

I'm confused. The CD4024 only has two input, clock and reset, and both are used and defined. There are 3 unused pins: 8, 10 and 13. It should make no difference if they are left unconnected. The two unused outputs on pin 3 and 4 should not be connected to ground. Notice I said to connect all inputs...
by jorg
Mon Mar 30, 2020 8:18 am
Forum: Eurorack Modules
Topic: Positive trapezoid LFO (synchronized to a square LFO)
Replies: 10
Views: 316

Re: Positive trapezoid LFO (synchronized to a square LFO)

felix le chat wrote:
Sun Mar 29, 2020 4:59 pm
Unless I understood incorrectly, these solutions work for the attack and top of trapezoid stages, but not that well for the decay
Luke's Maths solution provides separate control of attack and decay; review it again.
by jorg
Mon Mar 30, 2020 8:14 am
Forum: Music Tech DIY
Topic: CD4024 Reset (Clock Debug)
Replies: 7
Views: 139

Re: CD4024 Reset (Clock Debug)

Never leave any inputs open on a CMOS chip. They will float randomly, causing erratic behavior, and may even float to a state that turns on CMOS pairs simultaneously, causing excess power consumption. Even if you are not using the associated outputs, you need to connect all inputs to something (typi...
by jorg
Sun Mar 29, 2020 10:13 am
Forum: Eurorack Modules
Topic: delays with 1V/octave time control
Replies: 24
Views: 737

Re: delays with 1V/octave time control

Felix, your best bet is to contact AJH Synth for details.
by jorg
Fri Mar 27, 2020 3:31 pm
Forum: Music Tech DIY
Topic: Help needed to identify old components
Replies: 12
Views: 246

Re: Help needed to identify old components

The small component inside may well be a capacitor, which would explain why it might read as an open circuit (not sure I understand your description of it being "dead"). Small RF coils from broadcast radio receivers and similar, pretty often have built-in capacitors to tune them to the desired freq...
by jorg
Fri Mar 27, 2020 3:00 pm
Forum: Music Tech DIY
Topic: Help needed to identify old components
Replies: 12
Views: 246

Re: Help needed to identify old components

salut batchas, this looks like a RF transformer from a bandfilter with 1 primary and a split secondary winding. Probably from an old radio or TV or theremin. Not useful for audio , I guess you can't check it with audio oscillators, coil impedances will be too low. google pictures for "bandfilter 45...
by jorg
Fri Mar 27, 2020 9:22 am
Forum: Music Tech DIY
Topic: BCY87 Question
Replies: 4
Views: 105

Re: BCY87 Question

You could also use BCM847; it's cheap, plentiful, and works nicely for expo converters, ladder filters, diff amps, etc. https://assets.nexperia.com/documents/data-sheet/BCM847BV_BS_DS.pdf BCM847 is SMT; don't know whether that's a problem for you. BCM847BV grade has Vbe matching to 2mV, compared to ...
by jorg
Fri Mar 27, 2020 8:55 am
Forum: Music Tech DIY
Topic: Help needed to identify old components
Replies: 12
Views: 246

Re: Help needed to identify old components

If you are checking this part with an ohmmeter, an inductor will appear to be a short. It's a coil of wire.

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