High-Performance Flashgun Slave Unit

For introduction, see Home Page. Contact me at david(at)caves...etc.


13 April 2011: I am out of stock of everything except the programmed microprocessor. I do intend to re-stock at some point and to make available some new designs, but I too little spare time at the moment.

19 Nov 2008: I am out of stock of all kits and ready-built units and I do not intend to re-stock for a few months - maybe not till 2009. You can buy ready-built units from Firefly Electronics and you can, of course built your own unit, based on my circuit, but you will have to obtain all your own components.

14 Sept 2007: Flashgun Isolator. This project is decribed below. You could also take a look at weinproducts.com/safesyncs.htm

13 March 2006: Digital Slave Unit: Revised software is now available. The new software (version 4) adds a 'permanent learning mode' so that the slave unit always understands what the camera is doing! The new version has been adapted to cope with long sequences of 'red-eye reduction' flash pulses too.

How to Order

see the Prices page

Available products

To order, see the Prices page
Standard Slave Unit for Cave Photographers
(SLV 023)


Quick ref: List of Features & Setting-Up Procedure

Build it: Information (PDF 280K)
Date: Sep-01. Revision: 06-Jul-05. Note: this document has not been updated with recent slight changes to the design, which is now at version SLV023. Updates are given in a set of appendices and, in addition to the above document, you should read SLV023 Kit Check (PDF 67K) and SLV023 Bill of Materials (PDF 61K). You may also wish to refer to the circuit diagram (PDF 76K).

Other stuff: Questions and Answers | Troubleshooting|PCB (Easy-PC version 8, 32K)

Out of stock

You can make your own PCB from the file listed to the left.

Digital Upgrade


This is an upgrade to the above unit, which is described in the document Slave Unit for Digital Camera (PDF 470K).
[CREGJ 57] Date: Sep-04. Revision: none

Other stuff: Notes for Upgrade Kit | PCB (Easy-PC version 8, 22K) | Gerber/Drill files (ZIP 5K).

Out of stock

You can make your own PCB from the files listed to the left - or try without a PCB

New Digital Slave Unit - works with digital cameras


This product is a replacement for the combination of the above two items.

Quick ref: List of Features | Operating Instructions

Build it: Information (PDF 560K )
Date: Jun-05. Revision: 23-jul-05, assembly-10.pdf

Note: The above document describes the version 1 software. The setting-up procedure for the present, version 4, software is different, so you will also need the following document...

Operating Instructions: for Version 4 software (PDF 64K)
Date: Dec-05. Revision: 14-Feb-06. operating-V4_draft3.pdf

Old stuff: Operating Notes for Versions 1 to 3 [PDF 59K] Date: Oct-05. Revision: 18-dec-05, operating-V1_to_3_draft5.pdf

Complete kits are no longer available

What's available...

  • Software upgrade (programmed PIC)
  • Fully-built units with version 4 software are available from Firefly.

To order, see the Prices page

Bulb Firer

Quick Ref: Bulb Firers

Build it: A High-Performance Flashbulb Firer – part 2 (PDF 240K)
[CREGJ 55] Date: Mar-04. Revision: none

Flashbulbs are still the professionals’ choice for cave photography. This project by David Gibson – which is an update to his article in CREG journal 45 (Sept. 2001) – describes a compact, microprocessor-controlled bulb-firer that includes ‘seated’ and ‘fired’ indicators and a boost circuit to produce 24V from the 3V supply.

No longer available

This project is currently suspended: I have no time to work on this any further, at the moment.

Infrared filter material

Quick ref: Infrared Filter Material

Cave photographers often make use of an infrared filter over a camera- mounted flashgun. The purpose of this is to allow the infrared light to trigger a slave unit, whilst avoiding illuminating the foreground of the shot with visible light.

No longer available

You can order your own filter material from the address given in the notes.

Flashgun Isolator

A Flashgun Isolator (PDF 268K)
[CREGJ 61] Date: Oct-05. Revision and corrections: 25-oct-05

(original article)

Digital cameras can be damaged by connecting them to a traditional design of electronic flashgun. In this article, David Gibson describes the problem in more detail, and updates his isolator circuit from CREG journal 60.

No longer available

This project is currently suspended: I have no time to work on this any further, at the moment.

What's in the kits?

Basic slave Unit SLV023 Out of stock

Digital Slave Unit SLV051 Out of stock

This page, http://site2.caves.org.uk/flash/newsletter.html was last modified on Sun, 09 Sep 2018 11:11:04 +0000
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