10 replies to this topic

[elspedo]

Hey guys been thinking of this idea ever since one of my old teachers did it, he made an LED tach which looked rli cool changing from green-orange-red but i want to make a mechanical one but cant find any info on the net of how to do it :s easiest way is to prob just buy a cheapo off ebay and change the dial and housing? but if anyone knows how to make an LED one could you let me kno as may incorparate the LEDs around the side of a custom mechanical one i just like a challenge

Edited by elspedo, 11 January 2008 - 01:00 PM.

[elspedo]

:bump:

someone must know how to make it, dont think i explained it to well, what i am trying to do is get a tachometer/rev counter and change the dial so that as well as having the needle where the numbers used to be LEDs would light up as the needle passes them, this pic may explain better

[attachment=47545:tachometer.jpg]

hope someone can help

[DaveRob]

The LED tacho you refer to is published in a book of circuits from Electronics today international, I actually built one years ago and they do indeed work. Its not designed as a tacho tho its a voltage divider circuit and simply lights up LEDS as a proportion of a ref voltage. The ICs are National semiconductor LM3915, LM3916 and LM3917 from memory. If you go to Nationals site the data sheets will prob have all the circuits you need. Alternativly Maplin electronics might still have the books for sale. Hope this Helps

DaveRob

[elspedo]

cheers i will have a look

[elspedo]

Had a look but it appears that the magazine went out of production in 1998 does anyone have a circuit that works for this? thanks in advance

[Ethel]

'n it's even Mini flavoured Clicky

also other car related geekiness

[langers2k]

Try this: Tacho diagram

If it works let me know and I may give it a go!

edit: You beat me! Note to self, check thread after search but before posting response...

Edited by langers2k, 13 January 2008 - 12:19 PM.

[redhotmini]

maplins electronics do an electronic tacho kit - only reason i know is because i bought one for my electronics coursework, because i could never get my one to work, so i bought the maplins kit, and stuck it all inside my own custom built casing.

[elspedo]

cheers will give it a go when i get some time and let you kno how i get on

[dklawson]

I bought a few of the 2917 chips last year to tinker with this winter. However, I wasn't going to use them for a digital gauge like you're talking about I want to try and use them to power the analog movement of the earlier Smiths gauges. For the analog circuit see:
http://www.ime.org.u...ng_LM2917N.html

I wrote the guy who was working on the analog tach board and found he stopped working on it before resolving the temperature drift problem he was experiencing with his circuit.

[Syed Malaysia]

Alternatively, just buy an Astra GTE dashboard off ebay...