discobob Posted March 11, 2021 Report Share Posted March 11, 2021 Sorry if this bores people but I am stumped!! Due to Brexit where getting a Pot (it does come with cable and mount and gear cog) from the manufacturer of my lads sim racing pedals costing circa £45 (only costs 8 euros and they will only supply 2 max) I have gone on the hunt for a Pot I can source from somewhere else. It is a 10K Linear pot D Shaft and I have found this - https://uk.rs-online.com/web/p/potentiometers/1548183/ and ordered 3 as it looked bang on the money. However on connecting it up to the rig and using the calibration software I am getting a logarithmic effect in that the signal (inverse to voltage) is low through most of the turn of the shaft and then shoots to maximum signal. Connect up the manufacturers one and it works nice an smooth. However I have taken it out and come back to my bench and got the avo on it - and at half turn I am reading 5k ohms - the same as a manufacturer pot. Trouble is I haven't got a dc supply to test with either Anybody any ideas??? Hopefully this won't drop to the bottom the page PDQ Quote Link to comment Share on other sites More sharing options...
billytheghillie Posted March 11, 2021 Report Share Posted March 11, 2021 WHOOOOOOAAAAHHHHH Way above my head ( what you talking about? ) sure someone will help you out, good luck. Quote Link to comment Share on other sites More sharing options...
Agriv8 Posted March 11, 2021 Report Share Posted March 11, 2021 All I can think is feed voltage all the ones we used on the touring cars were given a 12v feed from a cleaned supply. all I can suggest is running feed to the pot using a battery or batteries to correct voltage they take very little amps to run and check readings other longshot could it be picking up noise from something else motor ! sorry not really and expert either ! Quote Link to comment Share on other sites More sharing options...
Flyboy1950 Posted March 11, 2021 Report Share Posted March 11, 2021 I am no expert but I seem to remember that about 50 years ago I was building a R/C transmitter and one of the pots wouldn`t throw a servo properly. We soldered a resister of the correct value either end of the pot track and that sorted it. I guess that you would need a 5 ohm one. Shouldnt do any damage trying this but as I said I`m no expert, try at your own risk. Hope it helps. FB Quote Link to comment Share on other sites More sharing options...
discobob Posted March 11, 2021 Author Report Share Posted March 11, 2021 I will hunt around to try and sort out a supply - the voltage being supplied is 3.5v. the daft thing is that I am also doing a mod with a Hall effect sensor and magnets which will get rid of the POT - but I am looking at setting the lad up doing both to give him a bit of income from uk based sim racers!! Quote Link to comment Share on other sites More sharing options...
The Heron Posted March 12, 2021 Report Share Posted March 12, 2021 I was lost when you said pot 😂😂 Quote Link to comment Share on other sites More sharing options...
discobob Posted March 12, 2021 Author Report Share Posted March 12, 2021 19 minutes ago, The Heron said: I was lost when you said pot 😂😂 was you thinking about smoking it Quote Link to comment Share on other sites More sharing options...
cheddletonkev Posted March 15, 2021 Report Share Posted March 15, 2021 Have both pots got the same amount of rotation ? if they are different then obviously the track in the pot is different length which will effect how it works can you fit each pot into wherever it goes and then measure the voltage at the wiper when operating it then you can compare the two Quote Link to comment Share on other sites More sharing options...
discobob Posted March 15, 2021 Author Report Share Posted March 15, 2021 17 minutes ago, cheddletonkev said: Have both pots got the same amount of rotation ? if they are different then obviously the track in the pot is different length which will effect how it works can you fit each pot into wherever it goes and then measure the voltage at the wiper when operating it then you can compare the two I eventually traced it down to a bad solder contact - the trouble is that the "replacement" pot has through board connectors on it - not solder tabs. I have now set up a test bed using an Arduino which really helped trace down the bad connection as it was causing the USB port to trip - a quick re-solder and it was working exactly the same as the original. I have now found a supply from Mouser that has the solder tabs on which will overcome trying to solder to the legs or using the through holes which they are not meant to be soldered. Only trouble is the handling fee which means I will have to order more than I wanted for the first batch to bring them down into a reasonable cost. I now need to find a better cable that can be used with an RJ12 connector, and be robust and flexible - the stuff I have is either multi-strand (telephone cable) that is too thin for soldering or single which is too stiff 😞 (2 pair and is also poorly colour marked). Quote Link to comment Share on other sites More sharing options...
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