Subject: RE: Diodes and loop Tachs
Author: Jesse Open
Date: Jul 8, 2002, 4:13 PM
Post ID: 1710567191
Do you have access to an oscilloscope ?
David Washburn wrote:
| Those of you who are on the MGCL will note that I am still trying to get my Tach to work with dual coils and a Dyna. Here is a synopsis: My Eldorado/SP has been running cheerfully along as I attack its few remaining gremlins. I got a working Tach from Mark at Moto Guzzi classics and closely followed the instructions of Mr. Wayne Orwig. When attached to one coil it reads half the correct RPM. I made a clever little "Y" harness with two diodes and attached it to both coils but the resistance in the diodes seems to defeat the signal. I do not wish to fry my Dyna, should I try diodes with less resistance or perhaps someone has another idea? Oh ho! I think I get it now. The negative pole of the coil is always grounded until that contact is broken via points or Dyna box. Power is not going from the coil to the tach to make a signal it is the other way around. The tach must produce a low voltage which is sent to the coil (ground). When this is interrupted by the points or dyna that is the signal read by the tach. Carl Allison suggested that the signal from one coil might be "masking" the signal from the other. Any suggestions? David |
Is that the single malt talking or just another cheap WHINE ?