Ten Dollar Frequency Counter's - Thread #2 - Page 1
Forum section: electronics / projects

author: TheBay
author_rank: Unknown
timestamp: September 10, 2016, 07:03:59 pm
content: I couldn't reply to the existing thread so continuing in a new thread, mods may want to merge threads howeverThis 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.pdfThis is the exact item/seller I bought it from:http://www.ebay.co.uk/itm/191226437566

author: nugglix
author_rank: Regular Contributor
timestamp: September 10, 2016, 07:58:26 pm
content: 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 presetvalue. 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?

author: TheBay
author_rank: Unknown
timestamp: September 10, 2016, 08:03:21 pm
content: I noticed the linear regulator gets a little warm but not hot per say, however a little heat is quite useful for the TCXOWhat 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 moreQuote from: nugglix on September 10, 2016, 07:58:26 pm

author: nugglix
author_rank: Regular Contributor
timestamp: September 10, 2016, 09:17:27 pm
content: 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

author: TheBay
author_rank: Unknown
timestamp: September 10, 2016, 09:25:03 pm
content: Will be interested to see the photos tomorrowMine 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.Quote from: nugglix on September 10, 2016, 09:17:27 pm

author: nugglix
author_rank: Regular Contributor
timestamp: September 10, 2016, 09:34:08 pm
content: First steps of my radio experiments are here:https://www.eevblog.com/forum/rf-microwave/cheap-stable-vfo-design/msg950836/#msg950836This 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.

author: TheBay
author_rank: Unknown
timestamp: September 10, 2016, 09:59:44 pm
content: 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 tryQuote from: evb149 on September 10, 2016, 09:51:53 pm

author: nugglix
author_rank: Regular Contributor
timestamp: September 11, 2016, 07:31:01 am
content: 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!CheersGuidoEdit: spelling, what else *sigh*

author: TheBay
author_rank: Unknown
timestamp: September 11, 2016, 02:17:01 pm
content: Quote from: nugglix on September 11, 2016, 07:31:01 amThanks 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.

author: TheBay
author_rank: Unknown
timestamp: September 12, 2016, 07:16:31 pm
content: Had another Frequency meter arrive today from China, cost a grand sum of £6.991-500Mhz 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%3AITHere are some pics, the contrast on the LCD is better in real life and it still has the screen protector on it.

author: bitseeker
author_rank: Super Contributor
timestamp: September 13, 2016, 10:37:15 pm
content: Quote from: evb149 on September 10, 2016, 09:51:53 pmPerhaps 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-/401173460259Not as many digits, but supposedly covers 1 Hz to 50 MHz.

author: edavid
author_rank: Super Contributor
timestamp: September 13, 2016, 11:08:28 pm
content: Quote from: bitseeker on September 13, 2016, 10:37:15 pmThere 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.htmlYou 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.

author: TheBay
author_rank: Unknown
timestamp: September 13, 2016, 11:34:09 pm
content: Quote from: edavid on September 13, 2016, 11:08:28 pmI'm going to have to get one of these too!

author: bitseeker
author_rank: Super Contributor
timestamp: September 13, 2016, 11:36:33 pm
content: @edavid: Nice find! I hadn't started price hunting, yet, when I posted. Thanks for the link.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 14, 2016, 12:23:19 am
content: 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.

author: ez24
author_rank: Super Contributor
timestamp: September 14, 2016, 12:48:04 am
content: With a casehttps://www.aliexpress.com/item/DIY-Kits-1Hz-50MHz-Crystal-Oscillator-Tester-Frequency-Counter-Meter-Case/32545690655.htmlEdited URL

author: bitseeker
author_rank: Super Contributor
timestamp: September 14, 2016, 01:00:47 am
content: 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

author: CJay
author_rank: Super Contributor
timestamp: September 14, 2016, 06:01:52 am
content: 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.

author: ElektroQuark
author_rank: Unknown
timestamp: September 14, 2016, 07:07:41 am
content: How do those work? Do they autoselect the most powerful signal they receive with the antenna?

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 08:50:47 am
content: Quote from: EdoNork on September 14, 2016, 07:07:41 amThey need to be close to the device transmitting.

author: TheBay
author_rank: Unknown
timestamp: September 14, 2016, 09:01:12 am
content: Quote from: edavid on September 13, 2016, 11:08:28 pmThis 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

author: TheBay
author_rank: Unknown
timestamp: September 18, 2016, 01:35:16 pm
content: 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?

author: mino-fm
author_rank: Regular Contributor
timestamp: September 19, 2016, 10:46:50 pm
content: Quote from: Alex Eisenhut on September 14, 2016, 12:23:19 amAre 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.htmYou 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#bsp7A simple 5-digit counter is shown here:http://mino-elektronik.de/fmeter/fm_software.htm#bsp13Sorry for german description.

author: lovemb
author_rank: Contributor
timestamp: September 26, 2016, 03:24:00 pm
content: Quote from: TheBay on September 18, 2016, 01:35:16 pmI 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

author: TheBay
author_rank: Unknown
timestamp: October 06, 2016, 10:44:44 pm
content: Quote from: lovemb on September 26, 2016, 03:24:00 pmInteresting, 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.

author: CJay
author_rank: Super Contributor
timestamp: October 07, 2016, 04:12:48 am
content: 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.

author: JPortici
author_rank: Super Contributor
timestamp: October 19, 2016, 11:31:06 am
content: I got one! I got one! Nice little thing.Has anyone already bothered to do a case with input/power connectors?

author: de0508
author_rank: Newbie
timestamp: May 25, 2017, 10:47:55 am
content: 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 and2) 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..

author: tablatronix
author_rank: Regular Contributor
timestamp: May 25, 2017, 01:16:10 pm
content: 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?

author: de0508
author_rank: Newbie
timestamp: May 25, 2017, 03:08:37 pm
content: 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.

author: vk3pb
author_rank: Contributor
timestamp: December 02, 2017, 01:54:40 am
content: HiI 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

author: cdev
author_rank: Super Contributor
timestamp: December 02, 2017, 02:18:28 am
content: 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" .

author: Old Don
author_rank: Regular Contributor
timestamp: December 03, 2017, 02:14:59 am
content: 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

author: chick0n
author_rank: Regular Contributor
timestamp: March 06, 2020, 07:10:05 am
content: 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?

author: Gyro
author_rank: Super Contributor
timestamp: March 06, 2020, 09:26:15 am
content: 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.

author: chick0n
author_rank: Regular Contributor
timestamp: March 06, 2020, 10:08:03 am
content: Quote from: Gyro on March 06, 2020, 09:26:15 amhttps://www.ebay.de/itm/1PCS-FUJITSU-SOP-8-MB506P-G-MB506P-MB506/152444966478They do work Ok...Execpt i cant configure to 1/64....Datasheet says:"It will divide the inputfrequency by the modulus of 128 or 256"Configuration Table in Datasheet:I attached SW1 and SW2 to VCC.

author: Gyro
author_rank: Super Contributor
timestamp: March 06, 2020, 10:28:17 am
content: Hmm, a European ebay sellernormallygives 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.

author: chick0n
author_rank: Regular Contributor
timestamp: March 06, 2020, 11:28:51 am
content: Quote from: Gyro on March 06, 2020, 10:28:17 amHmm...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.

author: chick0n
author_rank: Regular Contributor
timestamp: March 06, 2020, 04:33:00 pm
content: 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....

author: chick0n
author_rank: Regular Contributor
timestamp: March 06, 2020, 06:43:40 pm
content: I own another counter with MB506, this one can divide by 64....So the ones I ordered from Ebay are really fake / defect....

author: Gyro
author_rank: Super Contributor
timestamp: March 06, 2020, 09:14:42 pm
content: Quote from: chick0n on March 06, 2020, 06:43:40 pmOh 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.

author: Datman
author_rank: Regular Contributor
timestamp: February 11, 2023, 12:03:40 am
content: It can work down to a few Hz:https://www.eevblog.com/forum/projects/ten-dollar-pic-100khz-2-4ghz-frequency-counter/25/

author: wb0gaz
author_rank: Frequent Contributor
timestamp: June 26, 2025, 01:31:45 am
content: I am looking for source code for the device - I wish to modify it to add a menu entry that would display incoming frequency * 8, as I plan to precede the counter with HMC363 as a microwave prescaler.Not sure if this was covered elsewhere or more recently; this discussion thread hasn't updated for some time, so if there is a more recent discussion, particularly covering firmware update capability, I'd be grateful for a pointer!Thanks!