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Chinese frequency counter module - Printable Version

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Chinese frequency counter module - Mondial - 12-01-2016

This counter module was brought to my attention in this thread: 

http://philcoradio.com/phorum/showthread.php?tid=15414

Terry mentioned that they were selling for around $9 on ebay and I became interested and ordered one.

Well it arrived today and proceeded to try it out.

Must say that I am quite impressed. Reads dead on in frequency up to 70 Mhz or so and sensitivity is very good. In the photo it is reading a 7 Mhz signal at a level of only 10 millivolts.

It also uses very little power. I measured only 25 mA at 9VDC supply.

One of these counters could be incorporated into an inexpensive vintage signal generator for less than $10.

It really does not need an external supply, as all that would be needed is a diode and filter cap connected to the 6.3VAC filament winding to supply around 9 VDC for the counter. The counter input could be connected through a small value (470 pF) cap and series resistor directly to the signal output before the attenuator. That way, no matter what the output setting, the counter would always read the full level signal. 

The module is tiny and it could be built right into the generator box, or if you didn't want to modify it you could mount it in a small case and put it on top.

[img]IMG_2779.JPG[img/]

RE: Chinese frequency counter module - Radioroslyn - 12-01-2016

I tied mine to the cathode of the 76 osc tube in the 660 and used it to set the lo. worked fine from bc to 18.460. This model only goes down to 1mc, which is ok for bc osc 550+460kc. Also didn't notice any noise generated by it. Don't know what it uses for a time base.

RE: Chinese frequency counter module - Mondial - 12-01-2016

One thing to be careful of is input loading. The counter has a MOSFET front end and a pair of back to back protection diodes from input to ground, so if the signal is more than 0.7 v peak the diodes will conduct and load the measured circuit. Better to add a series resistor to reduce signal if it is at high level as in a tube osc circuit.

Actually, the time base is very good. It has a TCXO designed for use in cellphones, rated at 2.5 PPM.  Amazing the quality of mass produced parts these days. Better specs than expensive counters of a few years ago, and all for $9 including shipping!

RE: Chinese frequency counter module - Radioroslyn - 12-01-2016

Hey Mike,
Remember the good old dayz?
Dad had one of these. Darn thing probably cost 6 million buck back in '57.
Each digit had it's own 12AT7 to control it and would count up to 100kc.

Now only $10 and much lighter!!

RE: Chinese frequency counter module - Mondial - 12-02-2016

Now, that counter is the definition of a boatanchor!

Do you remember the Dekatron counters of the same era? These were neon tubes with numbered illuminated electrodes arranged in a circle. The indication would spin around as they counted.

https://www.youtube.com/watch?v=o3HLZOJKEQU

RE: Chinese frequency counter module - Radioroslyn - 12-02-2016

Help!!! I'm getting dizzy! And only bad things happen afterwords.
No actually haven't seen them before but I live a sheltered life  [Image: http://philcoradio.com/phorum/images/smilies/icon_lol.gif]
Morzh probably knows all about them! There from near his hood.
The vid after it is good too "Fun w/Dekatrons"

RE: Chinese frequency counter module - Phlogiston - 12-20-2016

I bought 2 of the 100khz to 60mhz models. Installed one using the dial lamp supply - rectified and a 2200uf filter, and that is all. Works great BUT is not accurate if the signal is modulated, so just turn the mod off & back on when you are ready.

The digit - 10mhz is not displayed. So you must know what it is, In other words 10mhz, 20mhz, 30mhz and so on look like 0.000.00, since it is not hard to see where you are at on a freq gen this is not a problem.

   

Too bad it isn't made here, but I have no complaints.

RE: Chinese frequency counter module - Radioroslyn - 12-20-2016

Good Job Russ!
Don't show Sam he left the same generator here for me to check over.
I've order a couple of the LF counters should be seeing them soon. Will
be using one for a digital dial for my old HRO. With PW dial and chart it's
hard to tell where your at.
Just as a quick note I took the static bag it comes in doubled it over and
used it as a screen for the display. Akin to putting a piece of smoked plexy
glass in from of it.

RE: Chinese frequency counter module - Mondial - 12-20-2016

Russ, if you add a momentary contact pushbutton switch, you can change the readout so that it toggles between the display you have now and one which will display the 10's digit with 100 Hz resolution. 

RE: Chinese frequency counter module - Phlogiston - 12-21-2016

The 10s digit I can deal with - until I forget to check the dial.

I'll try the static film. I kind of like the bright blue. I ran this module at 15V also. The display gets quite a bit brighter. I don't suppose that really ought to happen.

RE: Chinese frequency counter module - JaseSerre - 02-09-2017

Hi..i am a new user here. As per my knowledge the counter has a MOSFET front end and a pair of back to back protection diodes from input to ground, so if the signal is more than 0.7 v peak the diodes will conduct and load the measured circuit. Better to add a series resistor to reduce signal if it is at high level as in a tube osc circuit.

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RE: Chinese frequency counter module - Phlogiston - 02-09-2017

(02-09-2017, 11:50 AM)JaseSerre Wrote:  Hi..i am a new user here. As per my knowledge the counter has a MOSFET front end and a pair of back to back protection diodes from input to ground, so if the signal is more than 0.7 v peak the diodes will conduct and load the measured circuit. Better to add a series resistor to reduce signal if it is at high level as in a tube osc circuit.

I have found that I can overdrive it and attenuate the signal to the point that it can not be read. Also putting more than ~ 20% modulation on the signal will cause the reading to jump around about 5k.

RE: Chinese frequency counter module - Phlogiston - 02-09-2017

(12-20-2016, 09:38 PM)Mondial Wrote:  Russ, if you add a momentary contact pushbutton switch, you can change the readout so that it toggles between the display you have now and one which will display the 10's digit with 100 Hz resolution. 

Where would you put the switch?

RE: Chinese frequency counter module - Mondial - 02-09-2017

If you look at the back of the counter circuit board, there are two push buttons at the left. The lower switch is the one you are interested in. 

There are four terminals on the PCB switch. You want to connect one wire from your external switch to the lower right terminal on the PCB switch. The other wire from your switch connects to power supply ground, so when you press your external switch you are momentarily grounding the lower right terminal of the existing switch.

RE: Chinese frequency counter module - Phlogiston - 02-09-2017

(02-09-2017, 04:40 PM)Mondial Wrote:  If you look at the back of the counter circuit board, there are two push buttons at the left. The lower switch is the one you are interested in. 

There are four terminals on the PCB switch. You want to connect one wire from your external switch to the lower right terminal on the PCB switch. The other wire from your switch connects to power supply ground, so when you press your external switch you are momentarily grounding the lower right terminal of the existing switch.

Mine does not have the buttons. I'll look to see if the lands are there.