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frequency counter with offset for 10 Euro

Here testing with the Rubidium reference:

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Here the circuit diagram that nobody can read:

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Here the asm source code that nobody can assemble:

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Here the hex file in case you can program that into a PIC 18F14K22:

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What is so special about this apart from the LCD 4 Euro and the PIC 2Euro50 cents?

Well there are a few things,

1) You can specify (set) a prescaler value via RS232, actually 2, one for the internal (PIC) and one for any external one. 2) It has a software frequency comparator, it does PWM out that you can smooth with an RC network that you can use to drive a VCO. It will then slowly but Shirly move towards the frequency specified (also via RS232) on the top line of the LCD.

Of course all settings are saved in EEPROM.

This frequency comparator is only updated once per second, think of it as the integral part.. Its linear though..

I calibrated it, had no suitable trimmer, added a piece of coax to one of the crystal caps (22pF), and cut it till 10000000 Hz was displayed. The resolution with internal prescaler set to 4 is 4 Hz... It needs 4. Add external 256 prescaler and it is 1024kHz at 3 GHz.

My 10 Euro worth for this Sunday.

3) You can modify the code. 4) You can specify a frequency offset (+ or -) that is added to the display, say you measure a local oscillator in a receiver, specify the IF frequency as offset, and the counter shows the real frequency. 5) You can calibrate it to some point in software. 6) You can also switch off the PLL loop, and just set the PWM to some value, also via RS232 (control a light bulb?, or the LCD backlight?). 7) It shows the time too (after you set it).

It can be awfully accurate, used it for GPS experiments, now it is planned for the DVB-S 2.4 GHz control loop, if I do not decide to go FPGA for that.

As stand alone thing it can be very useful I think.

A useful prescaler for this to measure into the GHz range is the UPB1505GR:

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I have tested these, so for 3$ extra you go to 3 GHz.

What else? I will remember after I press post.

Oh, and it prolly needs a box.

9 V battery will do. Or a 3.8 V lipo, plus some switcher...

It does not make coffee, or pizza, but I had one anyways. Plenty of code space left for ??

Reply to
Jan Panteltje
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Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.
Reply to
Michael A. Terrell

On a sunny day (Mon, 20 Oct 2014 02:38:14 -0400) it happened "Michael A. Terrell" wrote in :

Neat. No PLL Mine also sends the frequency via serial oout. Resolution only 100 Hz? That would be a problem if you want to measure say audio range frequencies. I think I see up-down buttons, no adjustable prescaler, no RS232. Not tested on 1.1 GHz? It will do for many applications I am sure. But then for those I have this:

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Its smaller :-) No power needed.

Reply to
Jan Panteltje

1 MHz to 1.5 GHz. It's intended for use as a frequency display for a receiver. You can program an offset for the IF frequency. It has a six pin programming interface on the back. You can even program the brightness. There are Youtube videos showing how to set it up. There are a pair of programming pushbuttons on the back, as well. The configuration is stored in an EEROM. It was $14.40, US, delivered. There is a non english PDF for it as well.

It is model PLJ-0802-A

I bought it to fill in some missing channels on an old agile NTSC modulator to see if I can set the Aural channel on the old FM broadcast band.

--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.
Reply to
Michael A. Terrell

On a sunny day (Mon, 20 Oct 2014 04:32:27 -0400) it happened "Michael A. Terrell" wrote in :

Yes it is hard to compete with ebay.. That is why I suggested to meow? to get some stuff from ebay to teach the kids... OTOH to make, design your own is a lot of fun. In the late sixties I made a frequency counter with a 100 kHz crystal and nixi tubes,

5 digits, 7490 type decade counters, 7475 latches, some 74?? display drivers, 30 MHz or so maximum, the chips did not go any higher. The crystal was almost as big as this whole thing :-) I remember demonstrating it at some ham radio club, how you could have a digital frequency display. A bit later industry followed, those displays everywhere in radios.
Reply to
Jan Panteltje

7447, or 74LS47. I did similar, but I used fluorescent seven segment displays. 
--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.
Reply to
Michael A. Terrell

Ahhh! Happy days. Yes 7447 was 7 seg. Circa 1972 I used 7441 / 74141 for nixie tubes. My mainstay bench counter is nixie tube.

piglet

Reply to
piglet

I still have several HP nixie counters, although they all need some work after 40 to 50 years.

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--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.
Reply to
Michael A. Terrell

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