Readers' prototypes

Following the intermittent appearance of my ‘potted history’, regular reader and friend of EPE Thomas Stratford got in touch to say that he’d built a couple of my legacy projects! These photos show Thomas’s Uniboards Touch Switch and more recently, the Continuity Test Unit. In April 2020 during the CV19 lockdown, Thomas made my Soil Moisture Monitor from Nov. 1980.

The touch switch is a simple but very effective Darlington transistor design that relies on finger resistance to toggle a relay. The design would benefit from a proper p.c.b. with a pattern for the touch pads.  The Continuity Test Unit originally used some metal touch-switch pads from Maplin, which I used as contacts for testing fuses easily.  You can download the original circuits via my PDFs listings.

If you've tried any of my projects it would be great to hear from you.