Ten Dollar  PIC 100khz-2.4ghz Frequency Counter - Page 1
Forum section: electronics / projects

author: paulie
author_rank: Frequent Contributor
timestamp: March 22, 2015, 02:02:43 pm
content: I recently received one of these:http://www.ebay.com/itm/171506884137?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITI paid 10$ shipped on Aliexpress but same as the one for $12 and change on Ebay. Listing says temperature controlled oscillator but there don't seem to be anything like that on the board. May be a great deal but I can't find a PDF or link to user manual let alone schematic or code. No idea what the buttons do or screen options mean. Anybody have any experience or more iinfo on these?ps. More photos:

author: paulie
author_rank: Frequent Contributor
timestamp: March 22, 2015, 02:05:29 pm
content: I did find some vaguely readable text on another site but not really very helpful:Quote

author: dannyf
author_rank: Super Contributor
timestamp: March 22, 2015, 04:01:02 pm
content: QuoteS/he doesn't know.

author: dannyf
author_rank: Super Contributor
timestamp: March 22, 2015, 04:34:51 pm
content: They couldn't tell a tcxo from an ocxo? Possible.

author: paulie
author_rank: Frequent Contributor
timestamp: March 22, 2015, 05:06:41 pm
content: I do know the small metal can is not TCXO. It says "13.000 A545SA KDS 411" which, judging from other similar KDS parts in my stock, is not temperature controllable but just a generic SMD crystal oscillator. Also unlikely any commercial TCXO would be that tiny?ps. Probably typical chinese hype. Not worth opening a case though if I can get some use out of it. I'm surprised there are not more people out there familiar with this device because AFAIK there is no equal anywhere near this price range.

author: Howardlong
author_rank: Super Contributor
timestamp: March 22, 2015, 05:19:56 pm
content: No problem in getting TCXOs in small packages like that. I use 2.5x2.0mm TCXOs in my products, 2.0x1.6mm is becoming increasingly available too.

author: paulie
author_rank: Frequent Contributor
timestamp: March 22, 2015, 05:23:45 pm
content: Ok, so maybe these other KDS parts I have are also TCXO. Surprising there are not more zeros in the Mhz then. Anyway I would love to take advantage of this extreme accuracy if there were some hints around on how to use this thing. Many options and screens but no documentation.

author: Marco
author_rank: Super Contributor
timestamp: March 22, 2015, 05:48:02 pm
content: You can get the VFD one for a couple bucks more.Any way, found someschematics and docs. How's your Indonesian?

author: paulie
author_rank: Frequent Contributor
timestamp: March 22, 2015, 06:05:51 pm
content: Thanks. Those diagrams help a lot with the hardware and maybe those flow charts too. Indonesian is Greek to me but a lot better than the Chinese docs that the seller just sent me. Amazing there's no action around here on that. I guess they are right about the east/west technology gap changing.BTW I do like LED much better than VFD but if there was more info to be found there might learn to tolerate.

author: xrunner
author_rank: Super Contributor
timestamp: March 23, 2015, 02:00:46 am
content: Quote from: paulie on March 22, 2015, 02:02:43 pmI got one. It seems to be fairly accurate. I tried it on the 140 MHz and 440 MHZ ham frequencies and it was reading the correct freq. You can find a Chinese manual out there somewhere and run it through Google translate. I'll try to find what I got tomorrow.Quote from: blueskull on March 23, 2015, 01:56:37 amLOL - yea I was a little disappointed with that when I got it. Should have done an SMA

author: DanielS
author_rank: Frequent Contributor
timestamp: March 23, 2015, 02:25:19 am
content: Quote from: evb149 on March 23, 2015, 02:17:28 amWho uses digit drivers these days? Much simpler to use an MCU for both the segment driver and address decoder in most cases, especially when the MCU is already needed for other stuff to start with, such as (problably) a MHz+ counting input, the count "gating", gating period selection, polling of the external pre-scaler at said gating, etc.

author: rs20
author_rank: Super Contributor
timestamp: March 23, 2015, 02:45:26 am
content: TemperaturecompensatedXOs and temperaturecontrolledXOs are different things. OP said it had the latter, the quote from #2 proves it's the former.

author: Lightages
author_rank: Unknown
timestamp: March 23, 2015, 02:49:00 am
content: Hmmm, $10-20 for a TCXO 100KHz to 2.4Ghz counter with LED or VFD? 2.5ppm accuracy? Sounds like a deal! Too bad I can't see any specs on the sensitivity for the 60MHz to 2.4GHz range. Does it even work up to 2.4GHz?Still not a bad deal for someone who needs a counter and can't spend big bucks. There is more needed to make it useful of course. It needs a power supply if you don't want to use a battery or the lab PS. It should have a shielded enclosure with the needed switches and BNC or SMA connector and the proper cabling to the input front end as close as possible. Another problem is the input impedance. The specs only say "low impedance". This doesn't mean too much. It would cost probably another $50, or even more to make a stand alone instrument.xrunner, can you measure the input impedance of yours?

author: Marco
author_rank: Super Contributor
timestamp: March 23, 2015, 03:19:34 am
content: I posted a link to the schematics before.Input impedance is going to be nasty at the high frequency range, 4 1n4148 and two BF998R gates in parallel ... BF998R's which are connected in a really bizarre way by the way.

author: rs20
author_rank: Super Contributor
timestamp: March 23, 2015, 03:28:39 am
content: Regarding input impedance, how much does a high-impedance input 100kHz - 2.4 GHz buffer cost? Don't really know anything about high frequency, but I assume that's a module/block you can buy?

author: paulie
author_rank: Frequent Contributor
timestamp: March 23, 2015, 11:53:02 am
content: Quote from: rs20 on March 23, 2015, 02:45:26 amRe-reading posts you may see what I actually said was doubtful it had either. Those quotes don't prove anything except to the very gullible. For example use of the word "Warming" in one part of the spec from post #2 implies OCXO not TCXO.Elsewhwere in the spec use of the term TCXO only adds confusion. I personally know the difference having designed and worked with different versions of both (https://www.eevblog.com/forum/projects/worlds-smallest-cheapest-diy-temperature-controlled-oven/). I was surprised TCXO are available in 5032 even owning a reel of similar KDS inherited from my day job. Thanks to Howard I'm a little more up to speed on package variations.

author: paulie
author_rank: Frequent Contributor
timestamp: March 23, 2015, 12:12:08 pm
content: Quote from: DanielS on March 23, 2015, 02:25:19 amActually for small number of digits like here the 7seg LED is much cheaper, about a 5-10 cents each. Fraction of a Hitachi type LCD anyway. And generally better visibility.As far as driving direct there are nowhere near enough I/O to do that. Next size MCU up that can costs about 3x more. We don't have a schematic for the LED version but I do see a chip hidden under the display which might be the ubiquitous 74HC595 port expander. There's also an inaccessible pot under there, maybe brightness, which don't seem too bright to me.

author: bingo600
author_rank: Super Contributor
timestamp: March 23, 2015, 12:54:25 pm
content: Quote from: Marco on March 23, 2015, 03:19:34 amAny chance of getting the info attached here ?I'm not a FB user , and will never be/Bingo

author: Marco
author_rank: Super Contributor
timestamp: March 23, 2015, 02:09:03 pm
content: You don't have to log in ... you'll run into a bit of facebook js on tons of pages you visit, no reason to be afraid to simply visit the website.Here's the frontend though.PS. I think the BF998 will be little more than a couple of capacitors at 2.4 GHz.

author: codeboy2k
author_rank: Super Contributor
timestamp: March 23, 2015, 07:57:18 pm
content: Here's an imgur album of all the pictures from facebook.http://imgur.com/a/iENmk

author: paulie
author_rank: Frequent Contributor
timestamp: March 28, 2015, 10:08:04 pm
content: Well I've had a chance to check this counter out against 24 pcs Raltron RTX-231 and 2pcs Vectron T1175 20mhz TCXOs and they all agree within 2 counts (1ppm). Even over a few degrees temperature variation which amazes me. This is just about the best $10 I've spent in some time. Too bad it stops just short of being able to measure 32khz watch crystals. This would make it 10x more useful.I managed to figure out the bottom button scrolls sample window/resolution and filter and brightness menus. Not being fluent in Indonesian or Chinese I'm still not sure what the "Bit Set" (1f) function is for. Anybody have a clue?

author: codeboy2k
author_rank: Super Contributor
timestamp: March 29, 2015, 06:55:28 am
content: I don't have the unit, but google translating it I think it has something to do with the gate,or display of the gate, and it might do something with the decimal points that are used to display the gateTranslate says: (my comments inblue)ON: right numbers menu, bits last blanking(decimal point blanking? blinking? gate display? )OFF: normal viewpurpose: (1) the last blanking bit beat (blinking gate display in the last decimal point ?)figures to enhance the visual effect(2) When the gate 1S megabit and gigabit screen when 0.1s(when 1S gate, the display is MHz, when 0.1s gate, the display is GHz)They wrote blanking but perhaps they mean blinking.

author: xrunner
author_rank: Super Contributor
timestamp: March 29, 2015, 02:10:23 pm
content: Here's one in action. I'm transmitting on 449.500 MHz with 1 W and you can see what 's reading. If I attach a better antenna to it, it can correctly read the frequency of HF transmissions from my rig transmitting from an outside antenna while the unit is sitting on my workbench.I attached a text document that came out of Google translate, it's nasty ugly but you can make sense out of the menu system if you have the document open and have one of the units in your hand to play with.I've never found an original English manual anywhere.

author: paulie
author_rank: Frequent Contributor
timestamp: March 30, 2015, 03:39:58 am
content: Thanks for the text file. For some reason it came out better than the one translated from the one I was sent by the seller. Maybe the source was better, IDK. I was able to see that you can set an offset for the digits by using the "IF" menu but still don't know what the purpose of that is. Also no idea what the "]" menu is for. I'm just not good at this RTFM stuff even in english.BTW I also have one of those Baofeng radios. Unbelievable deal for the $16 I paid on Ebay. Very sensitive RX but the TX part is technically not quite legal here in the USA even if you use only the FRS or the other general walkie talkie band or even if you have a Ham ticket. Used responsibly though no harm done.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 30, 2015, 08:25:49 am
content: Quote from: paulie on March 30, 2015, 03:39:58 amMeasuring the local oscillator frequency of a receiver and then offsetting the value with either + or - the IF frequency will give you the receiving frequency.

author: paulie
author_rank: Frequent Contributor
timestamp: March 30, 2015, 10:15:43 pm
content: Ok, I see. "IF", intermediate frequency. I thought it was a "1f". So it's just a display convenience with no effect on the actual performance of the device. I hoped there might be some way to lower the readable range but still pretty good deal. The kindergarten explanation was appreciated. Like I said I'm not good at this even when the instructions are in english.

author: edavid
author_rank: Super Contributor
timestamp: March 30, 2015, 10:40:27 pm
content: Is the lower frequency limit set by the coupling capacitor, or is it enforced by software?

author: paulie
author_rank: Frequent Contributor
timestamp: March 30, 2015, 10:53:55 pm
content: Unfortunately it looks like a code limit. When it hits exactly 100khz the counting stops. Too bad because with new caps I was able to drop the lower limit on my "Gooit" AVR based counter to 4mhz from the original 30-40mhz. Like I said it would be nice to be able to adjust 32khz RTCC crystals. Still this is the most accurate counter around in that price range. Or even 10x more for that matter thanks to the ultra-stable precision oscillator.

author: opty
author_rank: Regular Contributor
timestamp: March 31, 2015, 09:27:11 pm
content: There is very similar LCD version:http://www.ebay.com/itm/0-1-1100-MHz-0-1-1-1-GHz-Frequency-Counter-Tester-Measurement-For-Ham-Radio-/111309861526though VFD is probably cooler looking.(there is error in the above auction, it claims MCU is PIC16F876A but pin count is not correct so I think it really is PIC16F648A, just like in all similar counters)It doesn't claim 2.4GHz (but I wouldn't trust that anyway), comes with 4 buttons so I guess browsing menu should be more intuitive.Linear regulator somehow gives me more confidence than switching one and @75mA lost power/heat isn't any problem.Does anyone know what is the 'Crystal measuring channel' ? I hate when no schematics/docs are linked with auction.They all come with ICSP programming interface to PIC16F648A, chances are someone will share open source code without that 100kHz limit. That would be great

author: paulie
author_rank: Frequent Contributor
timestamp: April 01, 2015, 07:15:16 pm
content: Yes, it would be nice if there was source for those floating around. Failing that I have AVR code for a similar counter so tempted to try a chip transplant. The MB506 spec is for 2.4ghz but I have tested this to well beyond 5.8ghz (tricky layout) and AFAIK there is no lower limit so might be possible to cover a huge range. Of course at these accuracies measuring watch crystal frequency is not practical so period comes along. Higher end (aka costing hundred$) like my Lutron PC1200 do both.It would be nice if this $10 one was smaller. The 3rd version shown below (http://www.ebay.com/itm/181532644600?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT) is quite small enough for my favorite 4aa case. However actual resolution is in question because there don't seem to be enough room for digits on that 0802 LCD. Not if there's to be decimal points or commas in there:

author: paulie
author_rank: Frequent Contributor
timestamp: April 10, 2015, 10:30:45 pm
content: Just now on Aliexpress there were 128 hits with "frequency counter 2.4ghz". For those who might be search challenged here's a link for one of them:http://www.aliexpress.com/item/0-1-60MHz-20MHz-2-4GHz-RF-Singal-Frequency-Counter-Tester-LED-Meter-Ham-Radio-Digital/32273662190.htmlStrangely they are now a couple bucks more than the Ebay link I posted couple weeks back. When I bought mine they were couple bucks less. They are even lower cost now there as seen here:http://www.ebay.com/itm/Blue-0-1-60MHz-20MHz-2-4GHz-RF-Signal-Frequency-Counter-Cymometer-Tester-/181666154685?pt=LH_DefaultDomain_0&hash=item2a4c2588bdIt's not uncommon for these guys to bump price a bit as sales pick up. Probably as a result of threads like this.

author: sa-penguin
author_rank: Newbie
timestamp: November 14, 2015, 12:53:47 am
content: I just got one of these, and I'm wondering:Where do you find the matching connectors for the power and RF inputs?

author: Datman
author_rank: Regular Contributor
timestamp: February 23, 2017, 10:01:25 am
content: About the TCXO: I think they sampled frequency error at some temperatures and they correct the value reading the actual temperature.

author: Luminax
author_rank: Regular Contributor
timestamp: March 01, 2017, 07:39:13 am
content: Translation in attached pictures.I'll translate the other page later this afternoon.-- Edit --Bah... the page just reloaded and my edited post went blank T_T... should always CTRL+A->CTRL+V before posting...Anyway TL;DR the DF one is Display Filter setting with ON filtering 200kHz and below frequencyand the lower parts sets some right shift bit set on or off... for ... decimal point?and the last setting for LED brightness

author: itsthatidotagain
author_rank: Newbie
timestamp: March 26, 2018, 07:39:21 pm
content: I know this thread is long dead, however for the record, here is an English translation of the manual for one of the 8 digit LED Frequency Counter Module Model PLJ 8LED C "sanjian studio" branded variant of this device.http://www.zl2pd.com/files/PLJ-8LED_Manual_Translation_EN.pdf

author: Datman
author_rank: Regular Contributor
timestamp: March 13, 2019, 10:26:00 am
content: Quote from: edavid on March 30, 2015, 10:40:27 pmQuote from: paulie on March 30, 2015, 10:53:55 pmHi all!I have just received my chinese cymometer. I had already bought a Victor 3165, but it has something like an its own personality... Only yesterday I noticed that it can also count decimals of Hertz in 1 second! For low frequencies it makes reciprocal counts!So I was looking for a straightforward frequency counter.Testing the "cymometer" I noticed that for square waves,in Low frequency mode, it can measure very low frequencies, down to 50Hz and lower! With sine signals, the frequency is wrong under 10~15kHz, because signal is clipped at the first stage, then filtered, so the final level is too low. If you select Auto mode, instead, are displayed alternately the effective frequency and a higher one.I'll remove the left display and search with the scope for the signal path. I should find a capacitor in the path. I have found a schematic, but I've seen a 10uF in the path, too high to block signals under 100kHz!I would also like replacing the two pushbuttons with a rotary encoder, using an Attiny: clicking on the encoder, it sends pulses to the upper pushbutton: rotating CW, it sends pulses to the lower one. Nothing happens rotating CCW.

author: Datman
author_rank: Regular Contributor
timestamp: March 13, 2019, 01:13:37 pm
content: This is the program for Attiny85 (Arduino IDE) (I still haven't tested it):Code:/*0.0 13/3/19 Completato. Funziona tutto?...*//* Per ATTINY85:1: I/O5 PB5 A0 RS2: I/O3 PB3 A3 - Entrata Encoder A (verso massa)3: I/O4 PB4 A2 - Entrata Encoder B (verso massa)4: GND5: I/O0 PB0 MOSI SDA - Uscita ENTER (clic)6: I/O1 PB1 MISO - Uscita UP (rotazione oraria)7: I/O2 PB2 A1 SCLK SCL INT0 - Entrata pulsante (verso massa)8: Vcc***************************Per avere un Bip ogni volta che si preme o si ruota l'encoder, è sufficiente collegarei catodi di due diodi alle uscite ENTER e UPe gli anodi al "-" di un cicalino piezoelettrico attivo (autooscillante) con il "+" a +5V.***************************PB0 ON: PORTB |=0b0000 0001 oppure |=0x01 oppure PORTB |= (1<<PB0)PB0 OFF: PORTB &=0b1111 1110 oppure &=0xFE oppure PORTB &=~(1<<PB0)PB3 ON: PORTB |=0b0000 1000 oppure |=0x80 oppure PORTB |= (1<<PB3)PB3 OFF: PORTB &=0b1111 0111 oppure &=0xF7 oppure PORTB &=~(1<<PB3)PB4 ON: PORTB |=0b0001 0000 oppure |=0x10 oppure PORTB |= (1<<PB4)PB4 OFF: PORTB &=0b1110 1111 oppure &=0xEF oppure PORTB &=~(1<<PB4)*/byte S; // Lettura dei due valori dell'encoder.byte So;// Lettura precedente dell'encoder.int X; // Usato in encoder() per evitare letture multiple.void setup(){pinMode(2, INPUT_PULLUP); // Pulsante (verso massa)pinMode(3, INPUT_PULLUP); // Encoder A (verso massa)pinMode(4, INPUT_PULLUP); // Encoder B (verso massa)}void loop(){// ------------- L'encoder è stato premuto? -------------if(digitalRead(2)==LOW){PORTB&=0b11111110; // Pulsante premuto: manda un impulso a massa di 50ms su ENTER (PB0).delay(50);PORTB|=0b00000001;while(digitalRead(2)==LOW); // Attende che venga lasciato il pulsante.}// ------------- L'encoder è stato ruotato in senso orario? -------------// Il valore binario di S rappresenta A e B.// Il centrale dell'encoder è a massa, quindi faccio complemento a 3 (=0b00000011).// PB 76543210S=3-(PINB>>3)&0b00000011; // L'encoder sta su PB3 e PB4, perciò scorro a destra di 3 bit prima di fare l'AND.// S=3-PINB&B00000011; // Se gli I/O 0 e 1 fossero PB0 e PB1, non dovrebbe scorrere a destra.S^=S>>1; // Faccio XOR (^) fra S (gray) e il suo bit 1, facendolo scorrere a Dx: AB XOR A,// ottenendo un binario che per ogni scatto fa 0-1-2-3-0 oppure 0-3-2-1-0.if(S!=So && S==0) X=0;if(X==0){if(So==1 && S==2){X=1;PORTB&=0b11111101; // Rotazione oraria: manda un impulso a massa di 50ms su UP (PB1).delay(50);PORTB|=0b00000010;}// if (So==3 && S==2){X=1; if(bipOn)Bip();} Rotazione antioraria: non fa nulla.if (S==0) X=0; // Non è stato mosso.So=S;}}It would also be useful modding firmware in the IF menu: now it is only possible adding or subtracting IF frequency, but if you want to disable the IF you have to adjust it to 00.000.000. We could add the "0" option to ∩ and U to disable IF.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 13, 2019, 04:06:12 pm
content: I have one of those. Attached is the manual I have (only in chinese, but you can more or less figure out most things - use Google translate if in doubt).There are probably many variants of the same design, so I don't know what's exactly on yours, but on mine there was a real 2.5ppm TCXO. Don't remember exactly how much I paid but it was definitely more than 10 dollars. You may have gotten ahold of a cheaper version with a standard oscillator.Anyway: it's fairly accurate, no problem with that. Now it has a very simplistic input stage (and connector) so don't expect wonders for high frequencies. For frequency measurements on digital signals up to 100MHz or so, which was my use case, I didn't have any issues. I kind of doubt you'll get much luck with 2.4Ghz signals, but please report back if you get around to testing that.

author: Datman
author_rank: Regular Contributor
timestamp: March 13, 2019, 07:46:43 pm
content: English translationCode:/*0.0 13/3/19 Finished. I have to check if it works...*//* For ATTINY85:1: I/O5 PB5 A0 RS2: I/O3 PB3 A3 - Encoder A input (to GND)3: I/O4 PB4 A2 - Encoder B input (to GND)4: GND5: I/O0 PB0 MOSI SDA - ENTER (switch) out6: I/O1 PB1 MISO - UP (CW) out7: I/O2 PB2 A1 SCLK SCL INT0 - Encoder switch input (to GND)8: Vcc***************************For a Beep each time the encoder is pushed or rotated, connect the cathodes of two diodes to ENTER and UP outputsand the anodes together to the "-" of an active piezo buzzer. Connect the "+" of the buzzer to +5V.***************************PB0 ON: PORTB |=0b0000 0001 or |=0x01 or PORTB |= (1<<PB0)PB0 OFF: PORTB &=0b1111 1110 or &=0xFE or PORTB &=~(1<<PB0)PB3 ON: PORTB |=0b0000 1000 or |=0x80 or PORTB |= (1<<PB3)PB3 OFF: PORTB &=0b1111 0111 or &=0xF7 or PORTB &=~(1<<PB3)PB4 ON: PORTB |=0b0001 0000 or |=0x10 or PORTB |= (1<<PB4)PB4 OFF: PORTB &=0b1110 1111 or &=0xEF or PORTB &=~(1<<PB4)*/byte S; // For reading the two encoder outputs.byte So; // Previous S value.int X; // Used to avoid multiple readings.void setup(){pinMode(2, INPUT_PULLUP); // Switch (to GND)pinMode(3, INPUT_PULLUP); // Encoder A (to GND)pinMode(4, INPUT_PULLUP); // Encoder B (to GND)}void loop(){// ------------- Did you push the encoder switch? -------------if(digitalRead(2)==LOW){PORTB&=0b11111110; // Pushed: sends a 0V 50ms pulse on ENTER (PB0) out.delay(50);PORTB|=0b00000001;while(digitalRead(2)==LOW); // Wait for switch release.}// ------------- Did you rotate CW the encoder? -------------// The binary value of S is the state of A and B.// Encoder closes to 0V, then makes complement to 3 (=0b00000011).// PB 76543210S=3-(PINB>>3)&0b00000011; // Encoder is connected to PB3 e PB4, then it shifts 3 times to the right before making AND.S^=S>>1; // XOR (^) between S (gray code) and bit 1, shifting to right: AB XOR A,// the result is a binary value changing "0-1-2-3-0" or "0-3-2-1-0" for each step CW or CCW.if(S!=So && S==0) X=0;if(X==0){if(So==1 && S==2){X=1;PORTB&=0b11111101; // CW: sends a 0V 50ms pulse on UP (PB1) out.delay(50);PORTB|=0b00000010;}// if (So==3 && S==2){X=1; } // CCW: do nothing.if (S==0) X=0; // Not rotated.So=S;}}

author: Datman
author_rank: Regular Contributor
timestamp: April 08, 2019, 08:20:38 pm
content: Hi allToday I've done some tests again. I removed the first display and measured on the collector of Q2 with my DS1054Z oscilloscope: I've seen many oscillations when Q2 goes to interdiction at about 65MHz. A 1nF capacitor between Base and Collector is useful, but it reduce bandwidth.With low frequency square wave signals it works much better: another problem is the slope of the wave on the collector of Q2. With a low frequency sine input, signal slope on the collector is poor. Signal on the collector should be squared by a Schmitt trigger. I'll try the 74LVC1G17.Uhm... Also a 74HC14 should work... I have an used one. I'll try it.

author: Datman
author_rank: Regular Contributor
timestamp: April 10, 2019, 08:10:28 am
content: Yesterday I've added the 74HC14. It works! Instead of the 1nF capacitor, I used 33pF between the collector and Gnd.Now it reads from about 20Hz. :-)The HC14 is mounted over the HC151D, with pins 1 and 14 aligned with 1 and 16 of the 151. I raised pin 12 of the HC151 and directly soldered it to Pin 10 of the overlying HC14. A short wire-wrap wire connects the disconnected track to pin 11 of the HC14.

author: Datman
author_rank: Regular Contributor
timestamp: April 11, 2019, 08:45:07 am
content: I replaced the 33p capacitor with only 6p8 between B and C. However, Schmitt trigger is required for reading audio frequencies.I have tested LF channel at 28MHz: it works. It should work at least to 40MHz. Can anyone suggest a common, cheap, not too small Schmitt trigger working to 60MHz?

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 11, 2019, 01:43:57 pm
content: Quote from: Datman on April 11, 2019, 08:45:07 amA 74AHC14 or 74AHCT14 should be ok @60MHz.

author: Datman
author_rank: Regular Contributor
timestamp: April 11, 2019, 03:10:21 pm
content: On ebay I can buy 5x 74AHC14 for 2.40+1.50€. If they are good, I'll buy them.

author: ebclr
author_rank: Super Contributor
timestamp: April 11, 2019, 04:23:15 pm
content: https://www.ti.com/store/ti/en/p/product?p=SN74AHC14DR

author: Datman
author_rank: Regular Contributor
timestamp: April 11, 2019, 05:09:15 pm
content: Thanks, ebclr. I was searching for shipping charges when I thought:"What is the multiplexer chip in which the signal goes after the Schmitt trigger?"It's a HC151D, and it is an active device, not a simple fet switch. Then, the HC14 can not compromise performance!...

author: mino-fm
author_rank: Regular Contributor
timestamp: April 12, 2019, 03:23:06 pm
content: For high impedance input you can use TLV3501. MAX961 has lower input impedance but can operate more sensitive. 8-pin SOIC offers a separate inverted output wich can be used to generate a hysteresis away from main signal: inverted output -> divider -> inverted input.Both parts opperate up to 100 MHz.

author: Datman
author_rank: Regular Contributor
timestamp: April 12, 2019, 09:29:42 pm
content: I've tested the program for the rotary encoder:- It was missing the declaration of the output pin.- Now the Enter switch is connected directly to the counter.- I mistakenly connected the "UP" output to PB0 instead of PB1. It was more comfortable, then I changed the software instead of changing the connection.- I've added an active buzzer (5Vdc) on PB1.- I've added a delay to ignore pulses from fast rotation. Fast rotation pulses don't increment the value, because the frequency counter doesn't accept pulses at less than about 300ms from each other. The delay prevents buzzer from beeping, so you can rotate the encoder counting beeps and that will be the increment. :-)It works!Code:/*v0.0 13/3/19 Completato. Funziona tutto?...v1.0 12/4/19 Elimino la gestine del pulsante dell'encoder, che sarà collegato direttamente.Sposto l'uscita UP da PB1 a PB0, poiché erroneamente l'ho collegata lì ed è più comodo.v1.1 13/4/19 Metto il cicalino su PB1 e un ritardo di 290ms per evitare che possa essere rilevato unaltro passo di rotazione prima di 310ms: il frequenzimetro non lo accetterebbe,ma il buzzer suonerebbe comunque.}*//* Per ATTINY85:1: I/O5 PB5 A0 RS2: I/O3 PB3 A3 - Entrata Encoder A (verso massa)3: I/O4 PB4 A2 - Entrata Encoder B (verso massa)4: GND5: I/O0 PB0 MOSI SDA - Uscita UP (rotazione oraria)6: I/O1 PB1 MISO - Buzzer7: I/O2 PB2 A1 SCLK SCL INT0 - Entrata pulsante (verso massa)8: Vcc***************************Per avere un Bip ogni volta che si preme o si ruota l'encoder, è sufficiente collegarei catodi di due diodi alle uscite ENTER e UPe gli anodi al "-" di un cicalino piezoelettrico attivo (autooscillante) con il "+" a +5V.***************************PB0 ON: PORTB |=0b0000 0001 oppure |=0x01 oppure PORTB |= (1<<PB0)PB0 OFF: PORTB &=0b1111 1110 oppure &=0xFE oppure PORTB &=~(1<<PB0)PB3 ON: PORTB |=0b0000 1000 oppure |=0x80 oppure PORTB |= (1<<PB3)PB3 OFF: PORTB &=0b1111 0111 oppure &=0xF7 oppure PORTB &=~(1<<PB3)PB4 ON: PORTB |=0b0001 0000 oppure |=0x10 oppure PORTB |= (1<<PB4)PB4 OFF: PORTB &=0b1110 1111 oppure &=0xEF oppure PORTB &=~(1<<PB4)*/byte S; // Lettura dei due valori dell'encoder.byte So;// Lettura precedente dell'encoder.int X; // Usato in encoder() per evitare letture multiple.void setup(){pinMode(3, INPUT_PULLUP); // Encoder A (verso massa)pinMode(4, INPUT_PULLUP); // Encoder B (verso massa)pinMode(0, OUTPUT); // Uscita UPdigitalWrite(0,HIGH);}void loop(){// ------------- L'encoder è stato ruotato in senso orario? -------------// Il valore binario di S rappresenta A e B.// Il centrale dell'encoder è a massa, quindi faccio complemento a 3 (=0b00000011).// PB 76543210S=3-(PINB>>3)&0b00000011; // L'encoder sta su PB3 e PB4, perciò scorro a destra di 3 bit prima di fare l'AND.// S=3-PINB&B00000011; // Se gli I/O 0 e 1 fossero PB0 e PB1, non dovrebbe scorrere a destra.S^=S>>1; // Faccio XOR (^) fra S (gray) e il suo bit 1, facendolo scorrere a Dx: AB XOR A,// ottenendo un binario che per ogni scatto fa 0-1-2-3-0 oppure 0-3-2-1-0.if(S!=So && S==0) X=0;if(X==0){if(So==1&&S==2){X=1;PORTB&=0b11111110; // Rotazione oraria: manda un impulso a massa di 10ms su UP (PB0).tone(1,1000,50);delay(20);PORTB|=0b00000001;delay(290); // Impedisce che possa essere rilevato un altro passo di rotazione prima di 300ms:// il frequenzimetro non lo accetterebbe ma il buzzer suonerebbe comunque.}// if (So==3 && S==2){X=1; if(bipOn)Bip();} Rotazione antioraria: non fa nulla.if (S==0) X=0; // Non è stato mosso.So=S;}}

author: Datman
author_rank: Regular Contributor
timestamp: April 15, 2019, 10:44:27 am
content: I have updated the program for ATTINY.

author: Datman
author_rank: Regular Contributor
timestamp: May 13, 2019, 03:39:08 pm
content: Hi all.I've noticed that the display multiplexing produce strong noise on power lines, then I filtered 12V by a 2mH coil salvaged from a CFL and 100uF.

author: chaztech
author_rank: Newbie
timestamp: November 04, 2020, 08:32:39 am
content: I happened to come across your message(s)/post(s) concerning you needed more info on your purchase.Hope this link will help you (I have one also but in red display format)https://www.mpja.com/download/34279TEManual.pdfI have also provided The PDF as attachment PLJ-8LED-C

author: Datman
author_rank: Regular Contributor
timestamp: November 07, 2020, 03:42:04 pm
content: Thank you, chaztech, but please note it was already here:Quote from: itsthatidotagain on March 26, 2018, 07:39:21 pmThanks again

author: wb0gaz
author_rank: Frequent Contributor
timestamp: June 26, 2025, 02:54:32 pm
content: Interested in applying the 8-LED counter at the output of a HMC363 prescaler (12 GHz divide-by-8).Initial idea was to find the counter's source code and add a "multiply display by 8" feature, but so far searching for source code looks to be unsuccessful.New idea - replace the (13 MHz?) reference/clock with one that is 1.25 times higher - 16.25 MHz (that would shorten the counter intervals by 25% making the HMC363 output appear to be 1.25 times higher, so for example 12 GHz input would display 1200 MHz. This change would alter behavior without the prescaler add-in, but that's not a concern.If the CPU is PIC16F648A then the datasheet says 20 MHz clock frequency.Does this sound like a plausible direction?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 26, 2025, 08:53:20 pm
content: Quote from: wb0gaz on June 26, 2025, 02:54:32 pmSure, on paper.It seems hard to actually find a 16.25MHz oscillator, a quick look finds only Mouser show a ceramic resonator at 16.25MhzIIRC the original 13MHz is 'good', via a TCXO, and it's a shame to lose that, so you could PLL from that /4 * 5 to get 16.25MHz (eg maybe a HC390 + HC4046)Or you could synth 16.25MHz via Si5351/MS5351, or a RP2350 could take in 13MHz and output a DFLL 16.25MHz via PIO

author: wb0gaz
author_rank: Frequent Contributor
timestamp: June 26, 2025, 09:53:46 pm
content: Thank you, PCB.wiz --- I found the same thing (16.25 MHz is not a typical crystal/oscillator, 16.257 is too far off), so was also thinking SI5351 with a low-end MCU to initialize at power-up (that could be driven by TCXO or otherwise), with a 74HCT1G00 or similar to make 5V if necessary.There are also one-time (factory, distributor) programmed oscillator modules (silicon labs or whoever digested them made them and probably still does), but for a one-off that might not be easiest way.I've not been able find a schematic of the counter module that includes the CPU/display sections (only the front end stuff seems published), however, the CPU is a TSSOP package with clearly visible part number and the 13 MHz oscillator seems easy to remove (or cut the trace from one to the other.)I am assuming (hopefully the case!) that the CPU's core and associated timers/counters are all running from the same clock input (so that changing the CPU frequency makes it go somewhat faster, but more importantly, have a proportionally shorter count gate.) I suppose another hazard would be access time for the LED/button interface chip (sort-of a MAX7221.) I've never done any hands-on with PIC so this (changing the reference) seems in the end to be the easiest path forward.Thanks for the comment!Dave