Yeti Rambles

Ever on the lookout for new test gear to add to my collection I stumbled across the XR2206-based function generator. These can be bought as a kit pretty cheaply from AliExpress or from eBay, they're easy to put together and use offering 1Hz - 1MHz of range through the use of some jumpers. It has two output terminals, one that gives a square wave and one that gives either a triangle or sine wave, depending on the position of a jumper. The heart of the device is an XR2206 which is an "obsolete" function generator chip with some pretty good specs and a low external parts count.   I bought one of these kits because my ultra low THD sine generator (a Wien Bridge oscillator with a bulb) is fixed at ~1kHz and being able to steep the frequency (and use other waveforms) is a huge help in analysing a circuit  My Ultra Low THD Oscillator After building the kit I fired up Arta to measure the THD, the results were... disappointing, 2.7% if you set the amplitude right but around 4-5% m...

This is just a short post to explain the concept of an audio probe and the design I went with for mine An audio probe is a common device in audio electronics which allows you to poke at a circuit and listen to the signal at that point, this lets you work through the signal path and pinpoint any faults  While you could just connect a lead to an amplifier and poke the signal you risk damage to the amp with any DC that might be present at that point. While a lot of amps have an input cap which will block the DC it shouldn't be relied upon, for this reason we need to add our own cap As you can see from the picture below the construction of an audio probe is pretty simple, I have a standard audio jack with a ground clamp which stays connected to the ground of the signal, I then have a 100nF capacitor going to a banana jack that lets me connect a regular multimeter probe.  Some people take apart a lead or use the leg of the capacitor itself for probing but I've found that cumbersome...

Here's a fun little project I finished this weekend. A two-in-one cabinet simulator and headphone amp from "Deadastronaut", you can see their information here . As the name implies this pedal simulates the effects of a guitar cabinet, providing the same EQ and sound, this avoids that unprocessed DI sound that you get when not using a microphone and amp.  This particular cabsim has another trick up it's sleeve, a headphone out, which makes it the perfect candidate for a portable headphone amp. Think the Vox Amplug but cooler. This is very useful for silent practice when I don't want to be using my 40W Fender amp.  I've created my own veroboard layout which is a cut back version of the layout created by dylan159. It excludes any XLR out and indeed the line out. It doesn't save a whole lot of space on the board but you do save an op amp and have the ability to fit it in a smaller box.  After I had built and verified the circuit it was time to box it u...

I recently put together a mini pedalboard utilising my DIY PSU . This new board was a great idea and I'm currently using it more than my main board due to how focussed it is. The only downside to my PSU design is the fact that it's not isolated. This means I get some ground loop noise when I play directly into my PC via my interface.   The easiest way to fix this is to use a DI box that features a ground lift feature. I have some 10:1 "DI Transformers"  that I picked up cheap off eBay however with my testing these wouldn't work well passively. While I do plan to use these in an active DI, I'm impatient and took to the internet to buy a solution.  I quite quickly came across the Behringer Ultra-DI Model DI1000 (catchy name there guys). While I managed to find a handful of reviews online and a couple of videos I didn't find anything that went in-depth. There was no information on the frequency response or the distortion/noise levels. Without further ado here...

The Problem  I have built and bough quite a number of guitar pedals now and not only is my main pedalboard out of room, my power supply (Harley Benton PowerPlant Jr.) is at capacity. Rather than build a bigger pedalboard and upgrade my supply it made more sense to me to create a new, separate, board to take some pedals off my main one. Not only will this mean I don't have to spend any money it will also allow me to be more focused with the sound for each board so I don't have the "Jack of all Trades Master of None" board I currently do.  Now the obvious problem with this idea is that I have no way to power this second board, enter the DIY Power Supply. The Electronics There are a number of ways to create a DIY PSU be it a fully linear or fully switching design, or even a mix of the two. A decision also has to be made about where the PSU will draw it's power from, will it plug directly into the mains or be powered from a lower voltage source?  Luckily for me I had...

Here's my take on the Big Muff Pi. I started with the "Green Russian" circuit and added some modifications that make it my most versatile dirt pedal. It runs the gamut from clean boost to full on fuzz. I used the Tagboard Effects layout as a base. I'll start with the modification that's not obvious from looking at it which is the tone stack, I modified the values to more closely match the original circuit and provide what I thought was a better response.  As for the extra knobs and switches I'll run through them in order.    Bias Knob This 100k pot replaces the 100k bias resistor on the 4th stage transistor, turning this to the right brings the value down and further mis-biases the circuit. This lets you get some interesting effects even if it's not the most useful.  The further right the quieter your sound and the more gated it becomes, at the extreme settings you can get some truly weird noises where only your transients get through.  Tone Wicker  This ...