Butler Henderson Posted February 4 Share Posted February 4 Hello I purcahsed a bi-stable flip flop unit from China on ebay for not a lot for an intended projecty . It has a single 5 volt coil latching relay and each time the unit is triggered the relay contacts flip. Unfortunately the supplied relay is far too big being a 10amp model so I acquired a 2amp one. However that has a coikl with a resistance of 144 ohms whereas the 10amp one is 70 ohms. I have tried without success a resistor in parallel. Can anyone advise? Thanks Mike Link to post Share on other sites More sharing options...
RMweb Gold SHMD Posted February 4 RMweb Gold Share Posted February 4 Could you give a link of the 2A version? If not, perhaps a photo? Adding a resister in parallel will, at worst, reduce the current available for the relay coil to operate, and at best, do nothing! (..depending on supply..) Think of it as replacing the resister with another 144 Ohm coil, adding the second coil would not get the first coil working would it? Kev. 1 2 Link to post Share on other sites More sharing options...
Butler Henderson Posted February 4 Author Share Posted February 4 49 minutes ago, SHMD said: Could you give a link of the 2A version? Hello Kev https://www.rapidonline.com/hongfa-hfd3-005-l1-pcb-signal-relay-5v-dc-single-latching-dpdt-2a-71-4726 Link to post Share on other sites More sharing options...
Butler Henderson Posted February 4 Author Share Posted February 4 (edited) Heres a photo of the cropped PCB once I had removed the overlarge relay To check I had not damaged anything in the desoldering I reattched by test leads the original relay and it worked. Have checked the 2A relay on a 5v supply and it works fine. Edited February 4 by Butler Henderson Link to post Share on other sites More sharing options...
RMweb Gold SHMD Posted February 4 RMweb Gold Share Posted February 4 I think the simple answer is that you have bought a "latching" relay as the replacement to replace a "bog standard", (but bigger), original relay. The smaller replacement relay is not compatible with the circuit on the PCB. Kev. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted February 4 RMweb Premium Share Posted February 4 2 hours ago, Butler Henderson said: Hello I purcahsed a bi-stable flip flop unit from China on ebay for not a lot for an intended projecty . It has a single 5 volt coil latching relay and each time the unit is triggered the relay contacts flip. Unfortunately the supplied relay is far too big being a 10amp model so I acquired a 2amp one. However that has a coikl with a resistance of 144 ohms whereas the 10amp one is 70 ohms. I have tried without success a resistor in parallel. Can anyone advise? Thanks Mike Since the resistance is higher, that means the voltage required will be higher. I suggest that you try a 12 Volt DC supply and see if that works, before you try attaching anything to the circuit board. As others have said, adding a resistor in parallel with reduce the power available, not increase it. Link to post Share on other sites More sharing options...
Butler Henderson Posted February 4 Author Share Posted February 4 (edited) The PCB regulates to 5 volt and the relays have 5 volt coils. I had connected a variable PSU which I supplied 12v to the PCB. 2 hours ago, SHMD said: I think the simple answer is that you have bought a "latching" relay as the replacement to replace a "bog standard", (but bigger), original relay. Flip your right, I thought the original was a latching relay. I'll dig out a normal one. Edited February 4 by Butler Henderson 1 Link to post Share on other sites More sharing options...
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