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  1. cygnusv

    How to control the speed of a 24vdc pump from circulating water temperature?

    Hi Chris Typically Chinese, innit!! The 0-5 volt confuses me a bit. An initial thought that I had was a screw in temperature transmitter from a vehicle - but where does the 0-5 volt come in? I know that my lack of knowledge will involve a bit of 'hand holding' but it really is appreciated. Stu
  2. cygnusv

    How to control the speed of a 24vdc pump from circulating water temperature?

    I've found this PWM control and wonder what you think of its suitability (bearing in mind that I am a novice)? In the listing it specifically mentions external contols and even shows where to plug it in. Looks simple enough. My next concern is to find a suitable device to clamp onto the hot...
  3. cygnusv

    How to control the speed of a 24vdc pump from circulating water temperature?

    How straightforward would that be to do?
  4. cygnusv

    How to control the speed of a 24vdc pump from circulating water temperature?

    Good thinking. We have a bank holiday here this Monday but I have sent an email to them
  5. cygnusv

    How to control the speed of a 24vdc pump from circulating water temperature?

    Hello again from the UK In preparation for our next (cold?) winter I'm finally hooking our boat's multifuel stove up to provide heat to 2 small radiators and using any excess heat to warm our domestic hot water tank. We live on board all year round. I've just ordered the back boiler for the...
  6. cygnusv

    Rest in Peace, Kris

    The project he helped me with had been ongoing for a very long time. He designed a small circuit that I could understand and build. After 10 months all is still well. All the best to Donna and Kris' family from the United Kingdom, Stu
  7. cygnusv

    Suggestions for replacement of an electromagnetic changeover relay

    Thanks Tha fios agaibh, It could be a dust problem. Next time I'm working in the electrical cupboard I'll give it a go.
  8. cygnusv

    Suggestions for replacement of an electromagnetic changeover relay

    Hello again from an electrical novice in the UK! My old (1951) boat has 24 VDC, 230 VAC mains and 230 VAC from a 1500 watt inverter. We are prone to mains power cuts on the marina (from time to time), and for that reason I installed a Siemens electromagnetic relay some years ago. It's simple...
  9. cygnusv

    Rest in Peace, Kris

    I am so sorry to read of this. Kris was so helpful. R.I.P Kris, from the UK
  10. cygnusv

    Using a Varistor to solve a back EMF problem

    Update - and apology for absence! Computer failure lost me a lot of everyday data including contact details with this very useful and friendly forum. I received an email posting from the forum earlier today and was then able to get back in touch. The pump problem described in this thread has...
  11. cygnusv

    Using a Varistor to solve a back EMF problem

    Hi everyone Many thanks to all and particular thanks to KrisBlueNZ for the advice and the life saver diagrams. I fitted all the bits and pieces over the weekend and operated the pump in pitch black with the switch cover off. No sign of any spark at all at the contacts! Interesting to note is...
  12. cygnusv

    Using a Varistor to solve a back EMF problem

    Excellent! Thanks KrisBlueNZ. Got it! The Square D arrived yesterday and after a lot of looking I was able to find postage free and no minimum order here in the UK, so ordered the non-R version plus a couple of capacitors and got change out of a tenner. Your diagram makes the fitting of the...
  13. cygnusv

    Using a Varistor to solve a back EMF problem

    Thanks Kiwi The pump is a Johnson 24 volt rated (on the box) at 10 amps max. It delivers up to 5.1 gallons per minute. I'll have to try to borrow a clamp on ammeter to check actual current. We protect it with a 15 amp fuse. We live on board all year round and the pump is well used for drinks...
  14. cygnusv

    Using a Varistor to solve a back EMF problem

  15. cygnusv

    Using a Varistor to solve a back EMF problem

    I'm not rushing to fit the new switch, so 'cleaning up' the motor first has got to be the logical first step. Am I right in thinking that the capacitor should be connected across the +/- closest to the pump with the diode further away from the pump? If I use a large metal stud mount diode...
  16. cygnusv

    Hi everyone

    I didn't see this section until I'd already asked my first question, so apologies for that My name is Stu and I live on a boat in Northern England and have done for about 13 years now. I am not practised in the dark arts of electronics and am here to learn more, and do more of my own smaller...
  17. cygnusv

    Using a Varistor to solve a back EMF problem

    Hi Guys I must say I'm very grateful for the help, and your collective interest. The pump is a Johnson 24 volt DC rated at 10 amps max. Its design pressure is 42 PSI and the (AC) Square D is factory set for on/off 1.4BAR and 2.8BAR both top and bottom range is adjustable. As noted above this...
  18. cygnusv

    Using a Varistor to solve a back EMF problem

    Hi KrisBlueNZ Many thanks for the reply. In fact when I pressed the 'buy button' it went straight through to Mouser. If I'm forced, I will buy from them and pay their price - £12 for postage - for something that can be delivered by post for less than £1, but I don't want to let them get away...
  19. cygnusv

    Using a Varistor to solve a back EMF problem

    Hi everyone, I'm new here and looking to solve a problem I have with burnt out contacts on my boat. The problem is with a 24 volt fresh water pump that was continuously burning out pressure switches. I partially solved the problem by bypassing the pump's internal pressure switch and using a...
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