Category Archives: Electronics Design

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 »

Low-battery monitor with TC54 voltage detector

Update: The TC54 in TO-92 package is discontinued and unavailable. However, surface mount versions are readily available. Update: Adding an output transistor – see below. So you’d kind of like to know when the battery in your stompbox  is getting a bit flat but you’re not sure how to proceed. The first problem is that… Read More »

Phantom power – it’s spooky!

I’ve been looking at the design of direct injection (DI) boxes with a view to making a phantom-powered piezo preamp for a friend who has acquired an acoustic bass with a passive piezo pickup but doesn’t have a preamp for it.  He’s tried plugging it straight into the mixer – but has experienced major tone-suckage… Read More »

Testing and Matching JFETS

Update: Matching JFETs – Revisited here. Update: Kits available in the shop here. Update: Matched sets of JFETs available for sale here. We’re talking here about N-channel depletion-mode junction field-effect transistors. “Field effect” because the current flowing between source and drain is controlled by the electric field strength at the gate.  Impedance at the gate… Read More »

Which? Diecast Box

So I was trawling through the enclosures section of a few of my favourite suppliers and decided to buy a few different diecast boxes. It seems that the Hammond 1590B is the standard for a small diecast stompbox.  Fine, no problem, you can even get a pre-painted version.  But the 1590B isn’t the cheapest of… Read More »