Category Archives: Project

True Bypass Relay with Muting

Update – extra schematics and timing diagrams added (see below). Also TLP222G photo mosfets are available in the shop here. There has been discussion on Stompville here (in the comment section) and on about problems with audio clicks when using a relay for true bypass. The consensus seems to be that the answer is… Read More »

P48 Phantom power from 9V d.c.

Here are a couple of options for generating proper 48V phantom power from a 9V supply. Before we get stuck into the details I should point out that the quiescent current for the first option is about 27mA and for the second about 52mA, so don’t be thinking you can run this from a PP3/1604/6LR61… Read More »

reStomp re-amping box

Update: reStomp re-ampers now available for sale in the shop. I had an enquiry about re-amping and decided to look into the idea more closely. Traditionally, when recording a guitar (particularly an electric guitar), it is usual to experiment with the combination of guitar, pickups, effects and amplifier to get the required sound and record… Read More »

True bypass with latching relay

Update: Remote controlling the True Bypass here. Update: SMD version here. Update: True Bypass Relay with muting here. Update: True Bypass kits are available to buy in the shop here. I have used Arduino over the last twelve months or so for a couple of projects and I have been looking for an excuse to… Read More »

Altoids piezo DI revisited

I’ve had some interest in and feedback for my Altoids Piezo DI box and I have revised the design sufficiently to warrant a new post.  The new design has the following changes from the previous version: 1/4″ jacks on input and output Low-voltage monitor (TC54) on the battery supply Higher voltage zener (33V) Increase R7… Read More »

Hybrid chorus with MN3007

I wanted an analogue chorus-pedal for my modular stomp-box and after acquiring a few MN3007’s from Hong Kong, I decided to build the Hollis Zombie Chorus as a starter-for-ten – which I did – and I was a bit disappointed with the result.  It may be that the PCB design was sub-optimal or some component… Read More »

Altoids piezo pre-amp

Update: Fully built and tested Altoids Piezo Preamps are available for sale in the shop here. I’ve been taking my Altoids piezo DI box to open mic nights and have had some interest and feedback.  People seem to like the concept but are less impressed with the balanced output and phantom power – which is… Read More »

Altoids piezo DI box

There is an update to this article here. As I mentioned in my post on the vagaries of phantom power, I have been looking at designs for a compact self-contained box to connect an upright bass to the PA.  The bass pick-up in question is a piezo jobbie integrated into the bridge like the Fishman… Read More »

Clean Squeeze – Hollis Flatline Opto Compressor

One of the first stomp boxes I made (and arguably my favourite so far) is the Hollis Flatline Opto Compressor. We amended John’s original schematic amended to show the topology a little more clearly: The first stage of the TL072 dual op-amp is configured as a non-inverting amplifier. Now,  excluding the effect of the light… Read More »