PCB Exposure Tool

Such tools are available in electronic shops but you can also build your to your specific requirements.

External View

1. Exposure time adjustment
2. Exposure Start button
3. Exposure Reset button
4. Hole acting as a ON indicator

Global Internal View

Bottom: an aluminium sheet acts as a reflector and sends up UVs.
The UV light source: 4 UV tubes Philips TL 8W/05 not always easily available.
Right, tubes starters from mobile lights used car garage, there was a promotional offer.
Down, (front plate), the electronic timer.

Electronic Starters

These came from hand-held lights used in car-repair officines. They were sold at 5$ each ...

And the schematic, if you can't find a promotional offer ...

Timer

Can be set to an exposure time range of 1-15' using the potentiometer.
A push button starts the exposure and another one can reset the exposure before timer normal time.
Common exposure for the type of PCB I use is around 1'15".

Schematic comes from "Nouvelle Electronique - L'Incontournable N°5" December 2004.

Some mods were added:

• Button Reset added
• Trimmer replaced by an external potentiometer
• The original optocoupler MOC3020 replaced by a MOC3043. This one switching the load on only when passing main supply passes through zero.
• Printed board modified accordingly.

Please, note the Start push button should resist to the maximal load's current during a short time.

Back to top