How to hook up a Frequency Counter

- K
- kayvee
  
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posted
15 years ago

Tue, Sep 23, 2008 2:12 AM

Hey everyone!

I have this machine that *should* be switching on and off at a frequency of about 110-120HZ. It is powered by a 24DC power supply and is controlled by a 12.5W, 100Ohm Rheostat placed in series with the machine. It usually draws about 0.2A ~ 0.4A (fused at 0.5A).

As of now I have no way of telling what the frequency of the machine (it is very important that it is accurate), and I plan on buying a panel mounted frequency counter to rectify this problem... But looking at the stats of the frequency counters I can afford out there they don't like being given any more than 10-40mA.

Now the question is how do I hook up this frequency counter to measure my machine without hooking it in a fashion which would give it the full brutality of the current?

Once again, any input would be greatly appreciated and thanks again!

- E
- Electronworks.co.uk Electronic
  
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posted
15 years ago

Tue, Sep 23, 2008 7:56 AM

Is there a voltage you can measure anywhere in the system? You could measure the current being drawn by the device (by measuring the drop across the rheostat) or you could measure the slight drop in supply voltage on the machine side of the rheostat. Either way it is ikky.

Is there a moving part that can be hooked up to an opto coupler? This would be a better way of doing it.

Is the panel meter designed to be put in series with the current or is the current rating you are seeing a maximum input current if the input voltage rating is exceeded.

Please tell me more about the system

Thanks

Bill Naylor Electronworks.co.uk - Electronic kits for education and fun

- J
- John Fields
  
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posted
15 years ago

Tue, Sep 23, 2008 11:00 AM

--- If the counter is rated to draw 10-40mA at a particular supply voltage, then, regardless of what the supply can deliver, that's what it'll use and you needn't concern yourself with the "full brutality of the current".

Your hookup will look something like this: (View in Courier)

+24V>-----+-----------[REGULATOR]-------+ | | | [RHEOSTAT] | | | | | [YOUR MACHINE]---------|------->[COUNTER] | | | GND>------+----------------+------------+

If you can tell us more about the counter and the machine (Specifically, what the counter wants to see in terms of supply and signal input voltage and current, and what your machine can supply as a signal input to the counter) we can supply you with more details re. the hookup.

JF