Marv 965 #26 Posted July 12, 2013 Hey Old, Been interested in this project. I ordered the meter. Will continue to follow. You do great work. Marvin Share this post Link to post Share on other sites
posifour11 723 #27 Posted July 12, 2013 (edited) Chuck, my meter is on its way from Chinaland. I can swing through "the big city" on Sunday on my way home from drill. Edited July 12, 2013 by posifour11 Share this post Link to post Share on other sites
Save Old Iron 1,568 #28 Posted July 12, 2013 Thanks for the patience guys. I have been trying to find the "best" parts for circuit performance but Radio Shack carries so little anymore in the stores. The "right" parts may only be able to be ordered on line. I'm also trying to work with the issue of not having to use a $3 "in store" part when a $1 part can be ordered online. Let's at least get the circuit board and major in store parts list created. Hopefully I'll be able get to the list in the next day or so. You should be able to grab many of the parts and start construction in a day or two. Share this post Link to post Share on other sites
Save Old Iron 1,568 #29 Posted July 14, 2013 Here is the circuit we will be working with. I'm working on a parts list as I speak. Hopefully all following this will be able to obtain most of these items at Radio Shack. Stay tuned for a circuit explanation and a parts list. Share this post Link to post Share on other sites
Save Old Iron 1,568 #30 Posted July 14, 2013 (edited) Functional areas of the circuit are outlined in color. Components in the orange area are located on the tractor. The ignition points and primary of the ignition coil are shown. Components in the green area are used to shape the ignition points electrical signal and limit the voltage level to allow proper triggering of the tachometer electronics. Components in the purple area provide a stable voltage to the tach circuit by accepting battery voltage from 10 volts to above 16 volts and outputting a constant voltage near 7.5 to 8 volts to the tach circuit. This stable voltage will keep the tach reading from varying if the battery voltage varies. Components in the pink area display the RPM's on an analog meter and allow for calibration of the meter reading to show the correct RPM on the meter. Edited July 14, 2013 by Save Old Iron Share this post Link to post Share on other sites
Save Old Iron 1,568 #31 Posted July 14, 2013 working on a parts list now ....... Share this post Link to post Share on other sites
Save Old Iron 1,568 #32 Posted July 14, 2013 this is the best I could do with "in store" available parts from Radio Shack 555 timer.......................(1)pn 276-1718 breadboard...................(1)pn 276-170 adj volt regulator...........(1)pn 276-1778 4.7k resistors................1pk of 5 1k resistors...................1pk of 5 pn 271-1118 47k resistors.................1pk of 5 pn 271-1130 .01uf cap.......................(1) .1 uf cap........................(3) 10 uf cap.......................(1) hookup wire 220 uf cap.....................(1) 100k pot........................(1)pn 271-284 100k resistor.................1pk of 5 pn 271-1131 (or 200k pot) 5 volt zener diode..........(1)pn 276-565 8 pin retention socket....(1)pn 276-1995 You will have to decide on how you wish to proceed. Visiting the Radio Shack store will get you most BUT NOT ALL the parts you will need. Ordering from them online - or from another parts supplier such as Jameco.com will get you the RIGHT PARTS THE FIRST TIME. What you spend in shipping for an order you will save in gas and most likely frustration on not having all the parts you need at one time. Check out the Jameco website and decide if they have appropriate shipping charges to your area. http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDisplay?langId=-1&storeId=10001&catalogId=10001 Share this post Link to post Share on other sites
Save Old Iron 1,568 #33 Posted July 14, 2013 Circuit description to follow later this evening..... Share this post Link to post Share on other sites
Save Old Iron 1,568 #34 Posted July 14, 2013 Consider this homework for now - until I can post later tonight Share this post Link to post Share on other sites
posifour11 723 #35 Posted July 14, 2013 Amazing as usual. If I'm getting one thing online, may as well get everything online to save time and frustration. Share this post Link to post Share on other sites
Marv 965 #36 Posted July 26, 2013 my meter has arrived. Marvin Share this post Link to post Share on other sites
Save Old Iron 1,568 #37 Posted July 31, 2013 I have not forgotten about you guys. Work has been insane and I just got off 22 days straight without a day off. I'll be posting more in the next few days. Share this post Link to post Share on other sites
roscoemi 245 #38 Posted October 28, 2013 Have you guys ever finished this project? Share this post Link to post Share on other sites
posifour11 723 #39 Posted October 28, 2013 Not yet. I've been too busy to think and, I gather, Chuck has as well hope to slow down soon and get to building. Share this post Link to post Share on other sites
Save Old Iron 1,568 #40 Posted November 5, 2013 Wow. That time flew by fast. My apologies but things have been off the wall at work. I have a few weeks vacation coming up this month and I promise I will spend some time on this putting together a buy list. Radio Shack will not have all the parts needed and will generally be more costly then going to a reputable parts supplier for the hobbyist like JAMECO. Once we get the build list complete, we can start with the actual build of the circuit board. I plan to supply enough detail on the build to hopefully allow anyone else who may be interested to follow along and construct a useable piece of test gear. Share this post Link to post Share on other sites
andrewLL 17 #41 Posted February 27, 2015 This is very interesting, I had been trying to think how I could use an inexpensive car tachometer but could not find one for a single cylinder engine. They are generally switchable between 4, 6 & 8 cylinder modes so would need a circuit to reduce the number of electrical pulses to correspond to a 4, 6 or 8 cylinder engine. Your circuit seems much easier, did yet get finished and do you have a circuit diagram marked up with the component values? I'm sure I can translate the circuit on to some strip board and soldering up a circuit is no problem. Andrew Share this post Link to post Share on other sites
km3h 543 #42 Posted February 27, 2015 What happened to the rest of the project????? Share this post Link to post Share on other sites
Save Old Iron 1,568 #43 Posted March 14, 2015 (edited) We did wander off into the weeds on this one. The circuitry was taken from the breadboard stage to the final? functional perfboard stage Circuit layout is not critical for this project to perform properly, any buildup on perfboard will work fine. On a single cylinder Kohler, the points are opening and closing at a rate of 15 times per second (or 15 Hz) Simulating this frequency on a pulse generator results in a correct display of 1800 RPM. Increasing the frequency to 30 Hz, as would be seen on a single cylinder engine running at 3600 RPM, the display shows excellent linearity. The circuit is stable over a range of 6.3 volts to 35 volts and draws less than 0.010 amps. The circuit can be powered by a 9 volt battery with over 40 hours cumulative use from a single battery. Since the circuit will only be powered for minutes at a time, battery life in normal use will be over a year. The circuit can also be powered off the tractor battery if needed. A 5 volt internal voltage regulator is mounted on the circuit to provide stable and repeatable RPM indications over a wide range of power conditions. Edited March 14, 2015 by Save Old Iron Share this post Link to post Share on other sites
Save Old Iron 1,568 #44 Posted March 14, 2015 (edited) Conceptually, my intent is to gut an inexpensive handheld analog multimeter and install a custom fit perfboard inside a handheld case. After building and using the analog tach, I forgot just how much I would rather deal with a smooth operating pointer rather than jumping digits! I'm sure you folks will have a few questions. I only get on RS a few days a month, so please be patient if an answer is not immediate. Edited March 14, 2015 by Save Old Iron Share this post Link to post Share on other sites
Save Old Iron 1,568 #45 Posted March 14, 2015 I have also had a request to recalibrate the 3 cylinder setting of a Heathkit ID-29 to read 1 cylinder 4 cycle signals. I'll be giving that a go later this summer. 1 Share this post Link to post Share on other sites
Save Old Iron 1,568 #46 Posted March 14, 2015 Most recent schematic w/ updated values for filter capacitors 1 Share this post Link to post Share on other sites
19richie66 17,574 #47 Posted March 14, 2015 So could this be adapted to a magnum twin or command twin with magnetic coils/ no points? I have most of the parts except the digital readout. I wish I could write code so I could try to make something out of these Ti launchpad boards I have. Just cant seem to pick it up. Thanks for all the info so far. Share this post Link to post Share on other sites
Save Old Iron 1,568 #48 Posted March 16, 2015 So could this be adapted to a magnum twin or command twin with magnetic coils/ no points? . Sure can. Modifying the values / configuration of the trigger circuitry [R1 C1 D1] will allow triggering off one plug wire. Setup would be similar to a "tiny tach" w/ loops of wire around the sparkplug wire as the input signal. Share this post Link to post Share on other sites
Save Old Iron 1,568 #49 Posted March 16, 2015 Hmmmm .....with a little modification and a small telescopic antenna in the handheld case, we could most likely go wireless with this circuit. Share this post Link to post Share on other sites
meadowfield 2,650 #50 Posted March 16, 2015 great work Chuck - with a simple mod you can make it run from the stator. That will give you 18 pulses per second and smooth things out - it also makes it agnostic to the number of cylinders. Share this post Link to post Share on other sites
