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I thought it would be a good exercise as I learn more about circuits to annotate a schematic and describe and calculate the important features. Though in calculating some of the filter values, there's clearly some impedance considerations I'm not accounting for because some of these filters are...

Hey folks, I've been designing this Blackface-ish inspired preamp circuit. The thing is it inverts the output which I want to avoid. For stubborn reason I've been trying to avoid using another op amp for the task of re-inverting the signal, adding a bit of gain, and buffering the output. I've...

Hello, does anyone have a lead on schematics like the GAR2520 or OA10? I want to incorporate some of these into some designs, but ideally I don't want to have to buy one of the kits as I'd rather be able to convert to SMD to use in some of my own layouts? I know there are schematics of some of...

In Doug Small's book "Small Signal Audio Design" he suggests we get better control over our gain control by having the pot straddle to two feedback networks. However, I barely ever see pedal designs utilise this. Is there a downside? One I can foresee is that we might change the value of the...

I mentioned I was developing some lazy breadboard modules in another thread and there was some interest in the idea. I'm a pretty amateur designer so feedback and suggestions are welcome. I'll publish everything on my github so people can get involved and use the modules when they're done. I...

Hey folks. Given I design for myself and don't really have to worry about scale, I want to design things the "right way. I'm designing pedal and studio gear. I think for some stuff I will use a linear power supply that will provide +12/0/-12 using a 5 pin din connector, so not worried about the...

Further to my wondering whether we are analysing diodes a little deceptively, I thought I would test the transfer function, as that's what we're actually interested in at the end of the day? You can see some interesting data in this interactive plot...

Hey folks, thought I would give GPT-5 a go at some (?simple) circuit analysis. I'm not a circuit wizz myself so not sure how well it did but here is the analysis. You said: how is the frequency range determined in this circuit You said: yes please You said: I would like to create two...

Hey folks, I've been doing some testing with diodes using my breadboard, except I've run into an issue, no matter how I hook up the diodes, I'm always getting asymmetric clipping. It doesn't matter whether they are silicon, germanium etc. This is as measured with my oscilloscope using a 2.4v...

Using this schematic from AionFX to build a negative voltage supply for my bread board. I notice they have separate ground for the negative voltage compared to the input filtering. Is this necessary or just to minimise switching noise?

Alright, back with another round of Ge transistor testing this time the GT309B. These were quite a bit more expensive per transistor than the previous boxes I purchased. However if you want higher gain but low leakage these definitely seem worth taking a risk on. Out of 20, only 1 device is...

This quote on an old thread discussing diode Vf and knee made me realise, in a lot of circuit analysis, a lot is mentioned of the voltage but rarely the current. It made me want to do some simulations and examine this topic further. Thing is I've only ever used LiveSpice, does any have a SPICE...

Hey folks, just looking at this "tape simulator" schematic, the original schematic is on the left, what I'm wondering is, would there be any difference compared to the version of the right? I'm vaguely aware of the concept of diode ladders, but usually I think there are some resistors in the...

I've been reading up on diode softness and curve tracing and all that kind of stuff. 2 threads in particular have made me question some of our understanding of practicalities of measuring the softness of the clipping/conduction knee. Take this thread for instance on MOSFET clipping, in this...

If anyone has followed my recent NOS [PNP] Gemanium transistor box adventures you would know I now own a large number of ~40 hFE, low leakage Germaniums. These are obviously not at all suited for Fuzz circuits, but that's ok, I like more subtle pre-amp like effects a lot of the time anyway. My...

Here's the results for the box of 100 1T313V, though there were 4 or 5, 1T313B sprinkled in. The data sheet suggested a hFE range of 20 - 250 so I had high hopes there would be a nice range of gains in the box. However, as you will see from the results, that was not the case. In fact I would say...

Bought a box of 50 П416Б Russian NOS Germanium Transistors from eBay. Spent the day in between working chucking them in the TC1 tester, so take the results with a grain of salt I guess. Apparently these are known for being low leakage, in fact the TC1 did not report an Iceo for most of them...

TLDR: AVOID. Hey folks, so given that I'm sure these FNIRSI devices have popped up on people's radars I thought I would share my experience with the DSO-TC4, a combination signal generator, oscilloscope, transistor tester. I purchased this device primarily for the SigGen and Oscope abilities...

Hey folks, I have a question about using CMOS switching for potentiometers. (CD4053 in this case) I want to build a pedal that is a Tube Screamer and a SD-1. Both circuits will be on the same PCB, but I want each to be a "mode" with a push button (in this case because I like to build "studio"...

*Renamed the thread as it is primarily about FET designs. Hey folks, so I've been reading Merlin Blencowe's Designing Guitar Preamp book. One thing that has interested me is the effect of essentially a poor design leading to some current leaking into the grid of the follower and therefore...