rc car temp and tach ideas

Discussion in 'General Electronics Chat' started by adamclark, May 1, 2014.

  1. adamclark

    Thread Starter Member

    Oct 4, 2013
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    hey all,, I have a nitro powered rc car and need an accurate way to measure the engine temp and rpm's... Any ideas? I have thought of putting a magnet on the flywheel and building something to measure how many times per second it spins around. but this would put the tiny (.15) engine out of balance.. the temp shouldn't be that hard but im drawing blanks with the tach. I figure a thermyster with a 7segment display would do the job for the temp. Any suggestions on an ic to do the work?
     
  2. poopscoop

    Member

    Dec 12, 2012
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    Piezo element to detect the impulse of the cylinder firing (That is how those nitro engines work isn't it?). Can filter with an IC program to eliminate the noise of typical bumps and bangs.
     
  3. adamclark

    Thread Starter Member

    Oct 4, 2013
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    I never thought of that.. I was to concerned with some kind of mechanical device.. And yes that's how they work, kinda like a diesel-gas mix. It uses a glow plug with a battery igniter to get started, then the heat from combustion takes over to keep it running.. but in all, its just a 2-stroke engine..
     
  4. wmodavis

    Well-Known Member

    Oct 23, 2010
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  5. BillB3857

    Senior Member

    Feb 28, 2009
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    I would expect that the temp of the engine would normally exceed 158*F. Sounds like you are into the range of needing thermocouple type technology. Does this measurement need to be made while the RC car is in motion? If not, there are several multimeters on the market that have a temp measurement mode complete with a plug in thermocouple.

    Here is an example..... http://www.sears.com/craftsman-prof...p-03473756000P?prdNo=1&blockNo=1&blockType=G1
     
  6. w2aew

    Member

    Jan 3, 2012
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    A little white and black paint on the flywheel, and a led/photodiode combo to create pulses to measure rpm.
     
  7. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  8. Little Ghostman

    Member

    Jan 1, 2014
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    Thats how I would do it, nice and simple. Depending on temperature you could use a diode and measure the voltage drop across it, depending on the diode you should be ok for 200C.
    Out of interest how are you going to monitor the parameters? I am doing a RC helicopter, for the radio I am using a 8051 micro with built in transceiver, I am using the micro for measurements and sending back the data after reading any incoming packets, I will then display the data on the command module, in my case this is a very small and old notebook, but nothing to stop you using LCD etc
     
    adamclark likes this.
  9. adamclark

    Thread Starter Member

    Oct 4, 2013
    472
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    with these engines, you lean them out to make max power but to lean an you hurt them. I found temp charts for the exact engine that compare temp to a/f ratio. so the temp needs to be measured with engine at full operating temp. The big problem here is that the ambient air temp affects the overall temp of the engine. I am just looking for an easy way to adjust the a/f on the fly so I always make max power without destroying this expensive engine.. I have a laser temp gun, but to use it the vehicle needs to be stopped. I was thinking if I could use a 7seg display, I could see the temp change as I was actually driving it.
     
  10. adamclark

    Thread Starter Member

    Oct 4, 2013
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    This is just what I was looking for and I have everything in my parts box. Any schematics available for this or am I researching this one myself?
     
  11. Little Ghostman

    Member

    Jan 1, 2014
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    Have you considered a micro with a transceiver inside? Silicon labs do a number of them at different frequencies, it has a 8051 micro at its heart, so with this you could take a number of reading such as temperature,revs and whatever you want, then beam the info back at upto 1Mbps. I am going to use a similar system with my helicopter, each frequency band has upto 64 channels.
    It would also give you the option of having a fail safe system that could shut things down if they went wrong. Obviously not much good unless you can mess with micro's
     
  12. adamclark

    Thread Starter Member

    Oct 4, 2013
    472
    6
    my quadrotor spydrone has something like that built in.. but its all li-po electric not nitro.. I was thinking of just putting the display on the car itself.. never considered having it on my controller.. nifty, might have to drag out the arduino and give some code a shot... bought the damn thing months ago and I have never written a line of code in my life.. Maybe the raspberry pi could help out also.. schematic for the paint line led/photo resistor coming soon to be proof read by the pros here.. thanks for all the ideas my friends
     
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