| The Shop > Electronics & IC Programing |
| Cheap AC motor speed controllers? |
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| John Swift:
Hi Rich the universal motor works on either a DC or AC supply http://en.wikipedia.org/wiki/Universal_motor you will need to use an over size variac transformer to ensure you don't overload the winding at low speeds the ebay controller should work but going by the pictures of the minimal components on the PCB and the lack of an control IC I expect its more of a lamp dimmer ( like figure 4 - http://sound.westhost.com/lamps/dimmers.html ) I would not expect the ebay speed control has any way to compensate for changes in mechanical load on the motor but may be OK for use with the biax tool as an example this speed control circuit - http://www.aaroncake.net/circuits/acmotcon.asp has a feedback circuit to measure the motor current and compensate for variations in load the voltdrop across R13 is a measure of the motor current to run of 240V some component values will need changing another example - http://www.velleman.co.uk/manuals/k2636.pdf John |
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