? about techo generator

Discussion in 'General Electronics Chat' started by fire_galy, Aug 27, 2012.

  1. fire_galy

    Thread Starter New Member

    Aug 23, 2012
    how to test the tachometer
  2. cork_ie

    Active Member

    Oct 8, 2011
    Do you seriously expect an answer to this question?

    What type of tacho generator?, make? model?,
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Basically 2 ways:

    1) Add a second known good tach next to the unknown unit and compare outputs.

    2) Insert a known signal and observe the output.

    Note #1 begs the question of how you obtain the known good unit.
  4. takao21203

    AAC Fanatic!

    Apr 28, 2012
    I would welcome that complete sentences are used for forum posts.

    You don't have to write half a page but a brief "what, how, why" + schematics + photos makes it easier to produce a thread that potentially also will be useful for other people.
  5. Wendy


    Mar 24, 2008
    You go very fast, and when you get pulled over, you ask how fast you were going.
    shortbus, absf and BMorse like this.
  6. BMorse

    AAC Fanatic!

    Sep 26, 2009

    Just out of curiosity, is English your first language? It just seems as if you are using a translator for your posts.... (just wondering, don't take offense to it.)
  7. takao21203

    AAC Fanatic!

    Apr 28, 2012
    I am getting tired of this American/British english debate.

    Over all the years, I have actually never seen any direct explanation of my wrongdoings.

    I would welcome that complete sentences are used for forum posts.

    This is more towards a meaning they should be complete, or have to be complete.

    I mean I do not want just to suggest it. I want to imply that I consider it as appreciate.

    Or shall I say: I want to imply if I consider it as appreciate?

    I have learned many languages now, so what is "first language", is an interesting question- but,
    I don't have a good answer.

    Translation engines produce mostly wrong grammar and I mean grossly wrong.
    Have you ever used translation software, BMorse?
    Last edited: Aug 27, 2012
  8. vk6zgo

    Active Member

    Jul 21, 2012
    If it is an automotive Tachometer,it will probably require an input signal which depends on the number of cylinders in the engine,& hence the number of sparks per revolution.

    Many DIY projects in magazines recommend the use of low voltage mains rate (50 or 60Hz) with a suitable correction factor.
    For example,a 4 cylinder vehicle producing a frequency of 50Hz is spinning at 12.5 revs/sec or 750rpm---around idle speed.

    By fullwave rectifying the 50Hz,you may be able to check 1500rpm.

    If you have an audio generator,or function generator which gan either do a high enough level to clip into a fairly good squarewave,or generate one directly,you can probably test it with that.

    If it is the "strobe" type or is the type that you press against the end of a spinning shaft,the problems will be different,but if it produces an electrical signal anywhere inside,you should be able to work it out some way.
  9. BMorse

    AAC Fanatic!

    Sep 26, 2009
    Yes, I have used translation software, and it always comes out wrong in so many ways.... first language means it is what you have been speaking since you were first able to speak.... It just seems like the way you word some of your sentences seems uncommon for most "English" speaking people (But then again, American English is a bit different than British English). But like I have said, do not take offense to my question, just curious...
  10. cork_ie

    Active Member

    Oct 8, 2011
    We still have heard nothing from the original poster.

    Tachometer = RPM indicator. which could be on just about anything from a car engine, to a spinning disk.

    What has me intrigued is the ? ("question about" I assume) Tachogenerator.

    Only very few applications would require a separate tachgenerator.
    Pre-electronic marine diesels was the last time I heard of one.
  11. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Tachogenerators are used on large industrial equipment. They are a DC motor used as a generator (to give a feedback signal), and designed so the voltage output is very closely linked to shaft RPM. They are usually marked with a metal label specifiying "tachogenerator" and always having a marked spec of how many volts per RPM.

    I've seen tachogenerators as big as a beer keg, bolted onto the end of a DC motor the size of a Volkswagon. It's kind of amusing the tachogen being so big as its only task was to make an analogue DC signal, that drives a few small signal transistors on a small card which acts as the brain of the motor speed controller.

    When I asked the head engineer why they used a tachogen the size of a beer keg to produce a signal of a few mA the answer was along the lines of "That's the way it is done" and "That's the size of the coupling on the motor shaft". I never got a good answer, and suspect these days they just use more modern sensors like hall pulse generators etc.
    shortbus likes this.