Kain Posted June 25, 2005 Report Share Posted June 25, 2005 Recently I had to use some 12V electrical clutches that draw about 4A continuosly under operation. I wondered if I can make a simple 1 transistor switch that can take this whole load? I was thinking of common collector configuration with zener stabilizator in the base. I do not care of any ripple since it is just a clutch so let it get as much noise as it wants Quote Link to comment Share on other sites More sharing options...
Kain Posted June 25, 2005 Author Report Share Posted June 25, 2005 Oh, and by the way, I am trying to use this switch stright from 110VDC... Quote Link to comment Share on other sites More sharing options...
ante Posted June 25, 2005 Report Share Posted June 25, 2005 Hi Kain,I would be careful with the ripple as this can make the clutch slip under heavy load!Yes you can make a one transistor switch for this but more info is needed to give good advice.If you have common ground for 12 and 110Volts is interesting to know for one. Quote Link to comment Share on other sites More sharing options...
Kain Posted June 25, 2005 Author Report Share Posted June 25, 2005 Ok, here is a quick drawing of what I was thinking about. I was thinking about current limiting resistor in the collector, but I have the feeling I will be cooking my dinner on it... Quote Link to comment Share on other sites More sharing options...
ante Posted June 25, 2005 Report Share Posted June 25, 2005 If the load is the 12VDC clutch, dial 911 for the fire department right away!The transistor will illuminate briefly as it dissipates more than 500Watts! ;D Quote Link to comment Share on other sites More sharing options...
Kain Posted June 25, 2005 Author Report Share Posted June 25, 2005 Fantastic... So, besides calling 911 what can I do to make this thing actually work, or any other suggestion? Quote Link to comment Share on other sites More sharing options...
ante Posted June 25, 2005 Report Share Posted June 25, 2005 Hi Kain,Ok, sorry if I was a bit drastic there but the idea was not feasible as I see it. I think you need a transformer or a clutch made for 120Volts, those are the two possible ways. A more complicated way is to use PWM, it is done in some contactor circuits where 24V contactors are run from 80V. Maybe there are more ways, anybody? Quote Link to comment Share on other sites More sharing options...
Kain Posted June 26, 2005 Author Report Share Posted June 26, 2005 Yes, initially I thought about transformer, but then I decided to make it more challenging. Oh well, I guess it's too much of a headache. Right now i was just thinking about Phase Power Regulation. Since the sine wave is cut of at certain point, can't I just cut it at 12V and then rectify the 12VAC so I can get my 12VDC? Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted June 26, 2005 Report Share Posted June 26, 2005 I don't see why this is hard, just use a transformer to step down 110VAC to 12AC then use a bridge rectifier to give you pulsed DC and power the clutch from that. To alter the power level just use a phase controller on the mains side (a normal lamp dimmer from a DIY store) or use PWM on the DC side. Quote Link to comment Share on other sites More sharing options...
Kain Posted June 26, 2005 Author Report Share Posted June 26, 2005 Hi Alun. I didn't say it is hard, I just decided tro make it hard by avoiding transformers ;D. So you think that the Phase Power Regulation (light dimmer and so on) can do it stright from 110 VAC? Quote Link to comment Share on other sites More sharing options...
hamoodyjamal Posted June 26, 2005 Report Share Posted June 26, 2005 Hi, I don’t know if you need this, but it’s a good idea to add a smoothing capacitor in parallel to the output of the rectifier. Something like 200V 2200uF. TAKE CARE ABOUT POLARITY. Why don’t you use a transformer? It’s safer and more efficient than a resistor.Also, what’s an electronic clutch?Bye! ;D Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted June 26, 2005 Report Share Posted June 26, 2005 No smoothing capacitor is required for a clutch.And electroic clutch is a normal cluctch that's controlledelectronically.Kain a transfromer is the best way to do this, 60W torroidial transformers aren't that big, one of these with a phase control dimmer is your best bet. Quote Link to comment Share on other sites More sharing options...
ante Posted June 27, 2005 Report Share Posted June 27, 2005 Hi Guys,As I mentioned before ripple can be fatal to the clutch especially if the driven load requires near maximum torque! A “clean” DC voltage will prevent a slipping clutch! 8) Quote Link to comment Share on other sites More sharing options...
Kain Posted July 1, 2005 Author Report Share Posted July 1, 2005 Ok now, I tried the phase shift control and it works fine enough for my needs Quote Link to comment Share on other sites More sharing options...
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