I am presuming that the intention of "connecting wires together" was to avoid the resistance to change more than the max value of the pot, you do this by connecting the wiper to one of the end wires, which turns the 3-wire pot into a 2-wire variable resistor as used in PB6. If you need to lower the value range of the pot, you can add a fixed parallel resistor from the wiper of the pot/variable resistor to the end wire at "zero" position. For example a 5k resistor (or 4.7k) added to a 5k pot will turn it into effectively a 2.5k pot (with a slightly different control range than an actual 2.5k pot, but that is not significant in most pedal controls). I have modified my potbox with a parallel and series resistor: - the series resistor keeps a very low output even at "pedal up" so my motor is idling - the parallel resistor shifts the active range of the pot away from where the pot has developed a bad spot so I can do more than "on/off" control that it used to give.
Cor van de Water Chief Scientist Proxim Wireless office +1 408 383 7626 Skype: cor_van_de_water XoIP +31 87 784 1130 private: cvandewater.info www.proxim.com This email message (including any attachments) contains confidential and proprietary information of Proxim Wireless Corporation. If you received this message in error, please delete it and notify the sender. Any unauthorized use, disclosure, distribution, or copying of any part of this message is prohibited. -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of EVDL Administrator via EV Sent: Friday, February 13, 2015 8:27 AM To: Electric Vehicle Discussion List Subject: Re: [EVDL] PB-6 Extra Wire On 13 Feb 2015 at 8:12, Roland via EV wrote: > This third wire is the center tap of the 5K pot. It is use to limit > the speed of a low speed EV which limits the pot to 2.5K. Also you > could parallel the two end wires of the pot which will result in a 2.5K pot. > > > > Just cap off the center tap wire if you controller requires a 5K resistance. Roland, are you sure about that? I had a 3-wire potbox for my old PMC DCC- 96 controller, and unless my memory is failing me (which I admit is possible), the 3 wires were just the 3 normal terminals of a potentiometer - both outer ends and the wiper. It was not a tap. Bill, I would check the potbox with an ohmmeter. If I'm right, you should be able to find 2 wires that read 5k ohms across them at all times (regardless of potbox position). Those are the outer terminals of the potentiometer inside. Then, connect one lead of your ohmmeter to the remaining potbox wire (the wiper), and the other ohmmeter lead to each of the above two in turn. With one of the ends, you should see a resistance that varies from 0 to 5k ohms as you move the potbox lever. With your meter lead on the other wire, resistance should vary from 5k ohms to 0 ohms. To connect this potbox to most 2-wire-potbox controllers, use the pair of wires that varies from 0 to 5k ohms. (Warning, some controllers require a 5k to 0 range, so test with a light bulb before testing with your motor!) If Roland's description is right, your ohmmeter should be able to identify the two wires that vary from 0-5k as the lever position is increased. Those are the ones you want to use with most controllers. See the above warning. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
