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 »
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 »
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 »
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 »
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 »
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 »
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 »
I learned this technique a good few years ago from an old boy who was a prototype wireman for a large electronics company. I’ve never seen it mentioned on the Internet so I thought I would write it up as a how-to. You will need the following: Your circuit board – after etching and before… Read More »
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 »
So you’re mucking about with a stompbox and you want to change the boring old red LED for a shiny new white LED – but you’re not sure how to proceed… Over the last ten years or so, light emitting diodes (LEDs) have generally become much more efficient than they used to be (actually, the… Read More »