Ten Dollar Frequency Counter's - Thread #2

[TheBay]

I couldn't reply to the existing thread so continuing in a new thread, mods may want to merge threads however 

This is the existing thread: https://www.eevblog.com/forum/projects/ten-dollar-pic-100khz-2-4ghz-frequency-counter/

Just thought I'd add an update to this thread, there seems to be a slightly updated version of this available now.
I picked mine up for £8.72 on eBay, shipped from Hong Kong, only took about a week to arrive to the UK.

The device was in a typical Antistatic bag and labled as a Sanjian Studios PLJ-8LED, the PCB silkscreen has the model PLJ-8LED-R5,

I have to be fair, I wasn't expecting much for the money but it works really well!, as I'm a radio ham as well it will have many uses on my work bench.

Differences I can see so far to other versions are:

PIC Microcontroller is not on the rear, it's under the LED Segment display, not sure of the type without connecting to it Via the ISCP port or removing an LED Segment, it appears to be a QFN package.
There is a TM1639 LED Driver IC on the rear.

Voltage regulator is a ST L7805CD Linear regulator, I noticed some other versions have a switching regulator so pleased about this.

This was advertised as up to "2.4GHz" Some are advertised as up to "1.1Ghz", the prescaler is a Fujitsu MB506 which is the correct 2.4GHz part, I know some came with MB501's, however I doubt I will be using it on anything over 500MHz.

I tried it out on a few things and am very impressed for the price, there is one Gotcha though on all of these... On the signal input the red wire goes to ground rather than signal input, just pay attention to the boards silkscreen rather than the cable colour, they could have rotated the socket on the signal input to resolve this.

Here are some pictures of mine, also a picture of the firmware version, you can get this by holding the top button while applying power, but this will reset your settings too.

I managed to find a English manual online, with some additional information added, however this is for the C3 revision, but aside from PCB Layout/Component differences the operation is the same:
http://www.zl2pd.com/files/PLJ-8LED_Manual_Translation_EN.pdf

This is the exact item/seller I bought it from:
http://www.ebay.co.uk/itm/191226437566

[nugglix]

Hi!

Also have some of these, from aliexpress.
They have the same problem w/ the red/back signal wires.

Thanks for the link the manual!

I like the IF feature, where you can add/subtract the measured frequency from a preset
value. Makes a great counter for a radio.

Unfortunately my version creates heavy spikes on it's supply rail.
And it draws *a lot more* power than advertised.
The little bastard is getting quite hot, at least from brightness 6 upwards.

But still, nice gadget. Will use it in my homebrew radio.

Oh of course, I also got a blue one.
Can anyone remember the time where there were no blue leds?

[TheBay]

I noticed the linear regulator gets a little warm but not hot per say, however a little heat is quite useful for the TCXO

What version are yours, it will say on the PCB Silkscreen. Has it got a linear regulator or switching?

Yes I remember when Blue LED's were first available, I put them in everything!

Also very interested in the homebrew radio, please tell me more

Hi!

Also have some of these, from aliexpress.
They have the same problem w/ the red/back signal wires.

Thanks for the link the manual!

I like the IF feature, where you can add/subtract the measured frequency from a preset
value. Makes a great counter for a radio.

Unfortunately my version creates heavy spikes on it's supply rail.
And it draws *a lot more* power than advertised.
The little bastard is getting quite hot, at least from brightness 6 upwards.

But still, nice gadget. Will use it in my homebrew radio.

Oh of course, I also got a blue one.
Can anyone remember the time where there were no blue leds?

[nugglix]

Just checked mine. Works down to 6V. Very nice.
OTH, the red led version needs a signal voltage of at least 150mVp-p.

Blue led version has the 7805, the red led version a LM2940-5.
In general my blue version draws a lot less current than the red one.

Both version miss the LDS feature shown in the manual you linked above.
And also I can only switch between 1s and 0.1s gate time.

Blue and red boards differ.
Will show some photos tomorrow.

WRT the radio:
will be a AM and 160m ham band super.
ATM I'm working on the local oscillator and first mixer.
I think I got the oscillator schematic, but still need to build it.
Mixer will be a NE602.
So nothing fancy.


Edit: spelling

[TheBay]

Will be interested to see the photos tomorrow

Mine also does not have the LDS feature, I thought that is because mine is in Auto, maybe this did not work well so they removed it from the firmware.

The radio sounds great! you should put the project up on here if you find the time, I'd love to see the work in progress.
I use 160m a lot, mainly for local rag-chew with friends but have had occasional DX, have got quite far with WSPR on 160m as well.

Just checked mine. Works down to 6V. Very nice.
OTH, the red led version needs a signal voltage of at least 150mVp-p.

Blue led version has the 7805, the red led version a LM2940-5.
In general my blue version draws a lot less current than the red one.

Both version miss the LDS feature shown in the manual you linked above.
And also I can only switch between 1s and 0.1s gate time.

Blue and red boards differ.
Will show some photos tomorrow.

WRT the radio:
will be a AM and 160m ham band super.
ATM I'm working on the local oscillator and first mixer.
I think I got the oscillator schematic, but still need to build it.
Mixer will be a NE602.
So nothing fancy.


Edit: spelling

[nugglix]

First steps of my radio experiments are here:
https://www.eevblog.com/forum/rf-microwave/cheap-stable-vfo-design/msg950836/#msg950836

This probably needs it's own thread.
Thanks for beeing interested.

Btw, I'm not a licensed ham.
Just want to build a radio since I was 10.

[TheBay]

Sadly I don't have any way to test this below 100KHz, If I find a way of doing it I will be happy to try

IIRC the older versions of these modules would not work (due to FW limitation, not HW limitation that anyone mentioned) below 100kHz.  Is that still the case with these newer versions?
As someone mentioned in the other thread it would be nice to be able to do things like measure 32kHz signals or whatever with these.

[nugglix]

Good Mooorning!

Here are the promised pictures.

First (boards.jpg) are the two boad versions I have.
Upper (unconnected) is the red led one, lower the blue one.
Quite different I'd say.

WRT to frequency measurement.
See freq_norm.jpg for a 12.7MHz signal.
Compare w/ freq_low.jpg, which is a 200kHz signal.
Both using a Siglent SDG2000X func-gen.

I wouldn't use this counter below 1MHz signal frequency...

Btw, pictures taken while running the counter from 6V.

I hope the quality of the pics is good enough.

Hope it helps!

Cheers
  Guido

Edit: spelling, what else  *sigh* 

[TheBay]

Good Mooorning!

Here are the promised pictures.

First (boards.jpg) are the two boad versions I have.
Upper (unconnected) is the red led one, lower the blue one.
Quite different I'd say.

WRT to frequency measurement.
See freq_norm.jpg for a 12.7MHz signal.
Compare w/ freq_low.jpg, which is a 200kHz signal.
Both using a Siglent SDG2000X func-gen.

I wouldn't use this counter below 1MHz signal frequency...

Btw, pictures taken while running the counter from 6V.

I hope the quality of the pics is good enough.

Hope it helps!

Cheers
  Guido

Edit: spelling, what else  *sigh* 

Thanks for those pictures, yes they are certainly different!

I see the Blue one is a PLJ-8LED-R5 just like mine, I guess this must be the latest revision.
The Red one looks like it says PLJ-8LED-H2? but hard to make out.

I wonder if the red one has the LED driver under one of the LED's.

This layout has obviously been changed for a reason, assuming that's the reason the Blue one works better and uses less power.

Also will be interesting to mess around with the firmware, seeing as it has an ICSP socket, but I am yet to find any firmware files online.

[TheBay]

Had another Frequency meter arrive today from China, cost a grand sum of £6.99

1-500Mhz range. Don't have anything here to test outside of that range.
This one is based around a Atmel Atmega 48PA, with a Fujitsu MB501 Prescaler.
The Crystal is a plain through hole 20mhz with a 40pf variable capacitor for adjustment.
0802 LCD Display.

I have to say I put this through a series of tests and it also seems bang on with accuracy!, this is fitted with a SMA connector and came with a small stubby antenna.
It's powered via a 9v battery.

There are 3 holes for jumpers on the back, I think one is to enable programming of the Atmega 48PA, had a play with the others and seemed to offset the frequency up or down depending on what jumper, will have a play around with that though. There are also points for a 6 pin ISP header for programming.

One thing that shocked me by pure coincidence is the person/company that shipped it was exactly the same person as the LED Frequency counter in my first post, even though it was a totally different Seller on eBay, quite the coincidence as there are 10000's of sellers in China of electronics on eBay.

Will 3D print a case for this, could come in handy as a pocket frequency meter.

This was the listing:
http://www.ebay.co.uk/itm/331873981044?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Here are some pics, the contrast on the LCD is better in real life and it still has the screen protector on it.

[bitseeker]

As someone mentioned in the other thread it would be nice to be able to do things like measure 32kHz signals or whatever with these.

Perhaps try a lower-frequency module such as this one: http://www.ebay.com/itm/New-1Hz-50MHz-Frequency-Counter-Meter-Tester-Module-Digital-Red-LED-Display-J0Q5-/401173460259

Not as many digits, but supposedly covers 1 Hz to 50 MHz.

[edavid]

As someone mentioned in the other thread it would be nice to be able to do things like measure 32kHz signals or whatever with these.

Perhaps try a lower-frequency module such as this one: http://www.ebay.com/itm/New-1Hz-50MHz-Frequency-Counter-Meter-Tester-Module-Digital-Red-LED-Display-J0Q5-/401173460259

Not as many digits, but supposedly covers 1 Hz to 50 MHz.

There is another version of that one that is much cheaper:  https://www.aliexpress.com/item/DIY-Kits-RF-1Hz-50MHz-Crystal-Oscillator-Frequency-Counter-Meter-Digital-LED-tester-meter/32704505181.html

You have to assemble it yourself, and it doesn't have the BNC connector, but it seems like a good deal.  As usual, there are multiple sellers on AliExpress and eBay.

[TheBay]

As someone mentioned in the other thread it would be nice to be able to do things like measure 32kHz signals or whatever with these.

Perhaps try a lower-frequency module such as this one: http://www.ebay.com/itm/New-1Hz-50MHz-Frequency-Counter-Meter-Tester-Module-Digital-Red-LED-Display-J0Q5-/401173460259

Not as many digits, but supposedly covers 1 Hz to 50 MHz.

There is another version of that one that is much cheaper:  https://www.aliexpress.com/item/DIY-Kits-RF-1Hz-50MHz-Crystal-Oscillator-Frequency-Counter-Meter-Digital-LED-tester-meter/32704505181.html

I'm going to have to get one of these too!

[bitseeker]

@edavid: Nice find! I hadn't started price hunting, yet, when I posted. Thanks for the link.

[Alex Eisenhut]

Do any of these come with a simple serial port output of the reading? With let's say a 1 per second dump at 9600 baud?
That would be immensely more useful than a display, really.

[ez24]

With a case

https://www.aliexpress.com/item/DIY-Kits-1Hz-50MHz-Crystal-Oscillator-Tester-Frequency-Counter-Meter-Case/32545690655.html

Edited URL

[bitseeker]

Only this part of the url is needed (still kinda long, though):

https://www.aliexpress.com/item/DIY-Kits-1Hz-50MHz-Crystal-Oscillator-Tester-Frequency-Counter-Meter-Case/32545690655.html

[CJay]

These little counters are excellent value for money, they use a cellphone TCXO for stability and are pretty accurate out of the box, the ones I've had certainly compared well to my Racal with the high stability ovenised reference calibrated against a GPSDO/Rubidium standard.

The IF offsets are really handy too, selectable on the ICSP pins by applying a voltage, they make retrofit to a radio really simple.

WIsh I could find the firmware for the earlier version though as an unfortunate experiment with a PICKit3 means I've got a bricked one.

[ElektroQuark]

How do those work? Do they autoselect the most powerful signal they receive with the antenna?

[TheBay]

How do those work? Do they autoselect the most powerful signal they receive with the antenna?

They need to be close to the device transmitting.

[TheBay]

As someone mentioned in the other thread it would be nice to be able to do things like measure 32kHz signals or whatever with these.

Perhaps try a lower-frequency module such as this one: http://www.ebay.com/itm/New-1Hz-50MHz-Frequency-Counter-Meter-Tester-Module-Digital-Red-LED-Display-J0Q5-/401173460259

Not as many digits, but supposedly covers 1 Hz to 50 MHz.

There is another version of that one that is much cheaper:  https://www.aliexpress.com/item/DIY-Kits-RF-1Hz-50MHz-Crystal-Oscillator-Frequency-Counter-Meter-Digital-LED-tester-meter/32704505181.html

You have to assemble it yourself, and it doesn't have the BNC connector, but it seems like a good deal.  As usual, there are multiple sellers on AliExpress and eBay.

This one looks interesting for testing Crystals.

The EZM Studio kit looks very nice if using BNCs, not sure if it can test crystals though.
http://www.ebay.co.uk/itm/New-1Hz-50MHz-Digital-LED-Frequency-Counter-Tester-Meter-7V-9V-50mA-DIY-Kit-K7S5-/311679573075?hash=item48918cdc53:g:oLwAAOSw65FXtX59

[TheBay]

Noticed something unusual about this LCD frequency counter, it seems to be transmitting a low power beacon on 446.000MHz FM Modulation.

Can't find any information about this device anywhere online, there are 3 jumpers on the back, 2 of those seem to relate to a + or - offset on the frequency displayed but both different values!
I wonder if this was originally designed for a specific purpose other than a general frequency meter?

[mino-fm]

Do any of these come with a simple serial port output of the reading? With let's say a 1 per second dump at 9600 baud?
That would be immensely more useful than a display, really.

Are you able to programm an ATtiny2313? If yes you can use 'fmeter20.zip' to get a frequency counter 0,005 Hz - 1 MHz (up to 200 MHz with prescaler). With 20 MHz Xtal baudrate is 38400. The LCD is not necessary at all.
http://mino-elektronik.de/fmeter/fmeter.htm

You can find another low frequency counter using Arduino UNO board with serial data output. First version 0,016 Hz - 250 kHz and 2. version with internal prescaler up to 7 MHz: http://mino-elektronik.de/fmeter/fm_software.htm#bsp7

A simple 5-digit counter is shown here: http://mino-elektronik.de/fmeter/fm_software.htm#bsp13

Sorry for german description.

[lovemb]

Noticed something unusual about this LCD frequency counter, it seems to be transmitting a low power beacon on 446.000MHz FM Modulation.

Can't find any information about this device anywhere online, there are 3 jumpers on the back, 2 of those seem to relate to a + or - offset on the frequency displayed but both different values!
I wonder if this was originally designed for a specific purpose other than a general frequency meter?

http://i1086.photobucket.com/albums/j457/thebayuk/EEVblog/20160912_194009_zpst7l83b0f.jpg

I just bought this one, arrived in 8 days from freaking china to europe! Was so excited to test it and it's crap..or something is wrong with it.

I try it with both 433MHz and 315MHz car fobs and it displayed mostly 145MHz and 202MHz and sometimes 50MHz. Thought it needed a longer transmission so I checked those cheap garage remotes (433MHz) that keep transmitting as long as you press the button(checked with RTL-SDR) and got the same unusable results.

I don't think I have anything to test it at lower than 315MHz, but at these ranges it doesn't work. I guess I will reverse it a little and scope it when I have time.

EDIT: I made a very quick schematic of the part that interest me just by looking at bottom pcb tracks, didn't dismantle it yet. (MAY HAVE ERRORS!)
Component values were copied from pcb silkscreen, not measured (yet)!


=
EDIT2: I just checked with the scope and I get 6.76MHz going to atmega48 input, x64(configuration from MB501L) = 432,64MHz!! (yet it displays something completely different like 175MHz)
So the problem seems to be in the firmware

[TheBay]

Noticed something unusual about this LCD frequency counter, it seems to be transmitting a low power beacon on 446.000MHz FM Modulation.

Can't find any information about this device anywhere online, there are 3 jumpers on the back, 2 of those seem to relate to a + or - offset on the frequency displayed but both different values!
I wonder if this was originally designed for a specific purpose other than a general frequency meter?

http://i1086.photobucket.com/albums/j457/thebayuk/EEVblog/20160912_194009_zpst7l83b0f.jpg

I just bought this one, arrived in 8 days from freaking china to europe! Was so excited to test it and it's crap..or something is wrong with it.

I try it with both 433MHz and 315MHz car fobs and it displayed mostly 145MHz and 202MHz and sometimes 50MHz. Thought it needed a longer transmission so I checked those cheap garage remotes (433MHz) that keep transmitting as long as you press the button(checked with RTL-SDR) and got the same unusable results.

I don't think I have anything to test it at lower than 315MHz, but at these ranges it doesn't work. I guess I will reverse it a little and scope it when I have time.

EDIT: I made a very quick schematic of the part that interest me just by looking at bottom pcb tracks, didn't dismantle it yet. (MAY HAVE ERRORS!)
Component values were copied from pcb silkscreen, not measured (yet)!


=
EDIT2: I just checked with the scope and I get 6.76MHz going to atmega48 input, x64(configuration from MB501L) = 432,64MHz!! (yet it displays something completely different like 175MHz)
So the problem seems to be in the firmware

Interesting, though I have tested mine around 450Mhz+ and it displays correctly, could it be faulty and do you have an antenna on it as mine won't pick up anything without it.

[CJay]

I would be surprised if it could measure the frequency of a keyfob transmitter accurately, I've got a couple of Racal counters here which cannot manage that.

I think it's the modulation scheme used, to encode the bits they turn the carrier on and off which upsets frequency counters unless the gate time is faster than the bit length (which is unlikely).

I think if you get your hands on a cheap PMR446 or FRS handheld radio it'll work just fine and display the transmit frequency.

[JPortici]

I got one! I got one! Nice little thing.
Has anyone  already bothered to do a case with input/power connectors?

[de0508]

Hallo,

i got one and change the hardware, so that there are no more hardware faults.

These are on the ATmega48pa side:
1) missing wire AVcc to +5V and
2) a bias voltage to 2.41V on the T1 input.

On this way i wrote a new firmware, a reciprocal frequency counter.
3) So i must add a wire from T1 input to INT0 input.

Now i can set the MB501L preselector to 1:128 and the max. frequency that i can messured will be round 1.1GHz.

The new firmware will scale the value on LCD automatic.

If some one replace the MB501L with a MC12079 (1:256), the rf frequency counter will reach 2.2GHz, but i thing the both 1N4148 will not work propertly.

For every change of the prescaler value, the new firmware source must be changed on a prescaler define only.

What a nice diy hack..

[tablatronix]

Nice I have one as well and was gonna hack around with it a bit, waiting for my isp programmer to arrive, were you able to pull firmware ( write protected on or off  ? )

Also considering replacing the prescaler with 1/256 would be nice if you can get the firmware to handle it, I also like that this has 3 io built in for adding buttons for additional functions.

What do the current IOs do ? They seems to change scale?

[de0508]

Hello tablatronix,

i don't have check the funtion of the original firmware or want to download it.
The only goal was to write a modify frequency counter my firmware with my call and functionality.

What the Jumper J1-J3 in the original Firmware do, i don't know.

[vk3pb]

Hi

I have a project where I want to use one of these cheap chinese frequency counters to measure the frequency (60-70mhz) of a communications receiver. However the difference is that I want to connect an Arduino to the frequency counter and somehow read the frequency from the frequency counter. Can anyone suggest how this might be doable?
 
cheers Peter

[cdev]

The PIC 8 digit one I have allows you to add or subtract an arbitrary IF from the displayed frequency.  I don't know if its possible to extract the displayed frequency from it easily. There are two 5 pin connections to each of the two banks of 4 digits, which is likely the signal for the display so if you simply sniffed the signal on those pins - knowing what protocol the seven segment displays with decimal points used, that would be it.

Also there is a six pin header which may be labeled "USART" .

[Old Don]

One on Banggood in kit form:  https://www.banggood.com/DIY-Frequency-Tester-1Hz-50MHz-Crystal-Counter-Meter-With-Housing-Kit-p-1063307.html?rmmds=search&cur_warehouse=USA

[chick0n]

I need a cheap small 2.4GHz Counter.

So I ordered a PLJ-0802, its perfect... I even can set IF Offset +- 1GHz....

Except, it can only measure up to 1.1GHz.

It has the MB501 Prescaler, so I thought I can replace it, with the Pin compatible MB506 Prescaler, which goes up to 2.4GHz.

It even has "MB506" Imprinted on PCB.

The MB501 is configured to 1/64, the MB506 Datasheet says it can be configured to 1/64 too. But it seems, it can only scale to 1/128 or 1/256. 

Is it maybe possible to Hack the firmware, to accept 1/128?

[Gyro]

Did you buy the MB506 from ebay or aliexpress? If so, the chances are that it's a re-marked reject part or a fake. The datasheet seems quite clear.

Edit: Or you have a problem with the soldering of the select pins.

[chick0n]

Did you buy the MB506 from ebay or aliexpress? If so, the chances are that it's a re-marked reject part or a fake. The datasheet seems quite clear.

Edit: Or you have a problem with the soldering of the select pins.

https://www.ebay.de/itm/1PCS-FUJITSU-SOP-8-MB506P-G-MB506P-MB506/152444966478

They do work Ok...Execpt i cant configure to 1/64....

Datasheet says:
"It will divide the input
frequency by the modulus of 128 or 256"

Configuration Table in Datasheet:



I attached SW1 and SW2 to VCC.

[Gyro]

Hmm, a European ebay seller normally gives you a better chance of a genuine part. Maybe contact them and tell them it's faulty.

Did you read earlier in the thread (reply #28), it could be that the micro or whatever cannot handle 2.4GHz/64 and is aliasing - from the picture, the prescaler output is going straight into a uC pin.

[chick0n]

Did you read earlier in the thread (reply #28), it could be that the micro or whatever cannot handle 2.4GHz/64 and is aliasing - from the picture, the prescaler output is going straight into a uC pin.

Hmm...thats a possibility...is it possible to Filter the Output?

I will check the MB506 Output with Spectrum Analyzer today...

The counter has PIC16F648A MCU.

[chick0n]

Ok...I checked this crap with analyzer and signal generator...

"MY" MB506 isnt capable of dividing by 64. It looks like, only SW1 Pin is working.

The MCU of the Counter is capable of handling over 40MHz input, and is displaying 2.4GHz at 37.5MHz input.

I will try some other prescalers like MC12034 and MC12079....

[chick0n]

I own another counter with MB506, this one can divide by 64....

So the ones I ordered from Ebay are really fake / defect.... 

[Gyro]

I own another counter with MB506, this one can divide by 64....

So the ones I ordered from Ebay are really fake / defect.... 

Oh well, now you know. I had almost given them the benefit of the doubt myself with the aliasing theory!

It just goes to show that you can't even trust European ebay sellers for such things these days. 

[Datman]

It can work down to a few Hz:
https://www.eevblog.com/forum/projects/ten-dollar-pic-100khz-2-4ghz-frequency-counter/25/