Ultrasonic cleaning

[roy entwistleParticipant @royentwistle24699]

In response to Bikepete I picked the same model up at a car boot sale. The seller had emptied a tin of soup into it and was complaining that it wasn,t getting warm. I offered a fiver and got it including a basket, I sent it back to Walkers for a check up. I am more than pleased with it. Though I have had the pallets and impulse pin come free in a platform escapement I was using windscreen washer fluid

Roy

Edited By roy entwistle on 02/10/2016 22:10:59

[Neil WyattModerator @neilwyatt]

For the record the unit I used made a loud hissing/rushing sound – quite high pitched and you wouldn't want to be trying to concentrate while in the same room as it. It didn't upset the dogs, but they did look at me in a funny way whenever I switched it on.

I would guess a unit that just buzzes isn't as strong. The Allendale one has three modes full wave, half wave for 'gentler action' and 'degas'.

Neil

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Neil Wyatt on 03/10/2016 00:44:50:The Allendale one has three modes full wave, half wave for 'gentler action' and 'degas'.

The purpose of these modes is a little confusing for me. The transducers in these units are piezo ceramic devices attached to a horn to couple them to the tank. They are resonant at about 40 kHz with a high Q factor and are driven by a relaxation oscillator which uses the transducers as the main frequency determining components. So the output of the transducer will be a sine wave with some harmonics. It can't be full or half wave.

The power supply for the oscillator is usually a poorly smoothed rectified sine wave using a bridge (full wave) rectifier. Perhaps by half wave they mean that the rectifier is replaced by a half wave rectifier. This won't change the output waveform but will pulse it with a 50:50 duty cycle, halving the output power. Yet the Allendale unit has a power setting so why bother?

Degassing is done by heating the water and running the unit for about ten minutes so the degas mode seems to be unnecessary as well.

Does the manual give any explanation of these modes?

Russell

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