When making glycerine jelly slides it is difficult to get all of the bubbles out, using this heater you can work under a low power microscope to remove any bubbles and adjust the specimens as the light is not over bright.

The lamp used is a Small Edison Screw refrigerator bulb, 15 watts is too powerful so a diode is added in series to reduce it by a half. The diode is a 1N4007 or similar, ask an electrical shop for a 1 Amp, high voltage (at least 600 volts) diode and solder it to the bulb as shown, it does not matter which way it is connected. Sleeve the bare wires of the diode to ensure that it cannot short out, if you don't feel able to do this ask a competent electrician to do this part for you.

When you carve out the woodblock for the bulb, ensure that no parts of the bulb metalwork can be touched when you remove the glass screen. To prevent the glass screen coming out use 2 small pins in the side checking that they do not catch the slide when it is placed on the heater.

In use, place the slide on the heater and put a small blob of jelly in the centre, it should melt in a few seconds when any bubbles can be removed with tweezers and the specimen placed in position.

Editor's note: The author Brian Adams died in 2002 and will be sadly missed.
 

Editor's note: Note that a variety of articles on simple techniques and home made projects for the amateur microscopist can be found in the Micscape Library (look under 'Novice' or 'Techniques').

Disclaimer: these instructions are given in good faith, but no responsibility is accepted by Microscopy-UK, Micscape, OnView Ltd or its contributors for any damage to property or persons on using these projects. It is up to the reader to judge if a tip or project is appropriate and safe. As the author advises, contact a competent electrician if not familiar with safely making mains voltage electrical gadgets. Note that dropping the wattage of bulb with a diode is not recommended for higher wattages.