#881

[@dilbertnewton6864]

Fun little board. Here's my two cents suggestion, pair the test point with a ground pt for the little scope spring attachment.

[@joeteejoetee]

Fun little board. Here's my two cents suggestion: decouple (0.1 uF) the Vcc close to the collector to ground so the power supply clip-leads do not radiate, and it will "firm-up" the emitter's output signal. Ditto about the test point lacking a ground --> 2x 0.1" spaced pins would be ideal !

[@bjj6708]

I built mine on Friday, used pcb and ground pads with a 5mm diamond hole cutter ( was too small) especially at emitter q1 where 5 components met. Worked fine, but I added loop test points for freq counter/cro and included loop for ground connection and added an extra 1k resistor & led to indicate pwr and a diode in series for reverse polarity protection as well as a size d crystal socket as I have many size d (HC6) crystals. It even worked down to 3 volts, up to 15, didn't seem to care. Thanks for posting, Barry, VK2FP/AG7VC

[@argcargv]

One trick on surface mount transistors (sot23) that you got the emitter and base swapped on the pcb is to install it upside down.

[@IMSAIGuy]

I did not have the correct diode when I first built the kit, I used an SOT23 part wedged in. you can see the correct diode at 7:11

[@davidharms3562]

Great video! I appreciate you continuing to design new test boards. Ironically, I got a few of your Dual OP Amp test boards in last week. Looks like I’ll be ordering this one soon too. Thanks again! 👍🏻

[@argcargv]

I think the diodes in this circuit need to be high speed switching diodes like the 1n4148, not slower power diodes like the 1n4001. These would act more like capacitors at the crystal frequencies.

[@IMSAIGuy]

yes you are right. the thru hole has 1n4148 and I just used the SMD package for the 1n4001 but actually loaded a small signal diode

[@jordimoreno9122]

Great video and great design! Just made it the DIY way. Didn't have a ceramic 2uF capacitor, so I placed a 2.2uF electrolitic one. Are there any drawbacks on this? Apparently it's working just fine

[@IMSAIGuy]

that's fine

[@mariodistefano2973]

Hi!I was lookng for a circuit like this. But I need to test also ceramic resonators. Do you think this circuit will work as well?

[@IMSAIGuy]

probably better to use simple 7414 type oscillator. here is one: kzbin.info/www/bejne/fHbbf2uQltqZeas

[@SanthoshRamaraj]

Nice ending!

[@mr1enrollment]

I have a bit of a complaint about the circuit. Whenever I see a transistor base circuit without a R that (in the absence of signal), does not sink current - I suspect that some of the builds will not reliably turn off the transistor. So I would add an R in parallel with the 2uf. I know I am being pissy sorry. I have seen this too many times, and I am so so so sensitive,... LOL cheers

[@argcargv]

Yeah, if the transistor is high gain and the capacitor low leakage it might take a while for the led to turn off.

[@mr1enrollment]

@@argcargv Partly. It depends much on the leakage of the cap, which if high enough (awkwardly), that makes the circuit more reliable. Also the leakage current exiting the base tends to charge the cap, this is at odds with the leakage current. Adding an R across the cap, shifts the result toward discharging the cap in absence of the signal. AND: the world will not end if the R is absent.

[@argcargv]

@@mr1enrollment I agree that cap leakage here is helpful, but I just don't see how the base current can charge the cap. That doesn't match the models that I am aware of for BJT transistor behavior in this common emitter configuration.

[@mr1enrollment]

@@argcargv always some reverse current thru a PN junction. Magnitudes matter, i have not done due diligence. If the world ends up in peril, I'll take a closer look.

[@IMSAIGuy]

I just stole the design. It was first posted in Elektor magazine in the way back days but many have used it since.

[@ThinklikeTesla]

There are some nice SMT test point clippy things available, in case anyone wants to go full SMT. Keystone 5015 and it's cousins.

[@RideGasGas]

Just curious, why are the SMD components on one board diagonal but in another view on a different board they are on the normal H and V axes?

[@IMSAIGuy]

I did not have the correct diode when I first built the kit, I used an SOT23 part wedged in. you can see the correct diode at 7:11

[@RideGasGas]

@@IMSAIGuy Thanks!

[@Architector120]

2:30 What happens to D5 and D6? you're using P-N junction as a diode? does this mean that the circuit shown here 7:13 doesn't work correctly for some reason?

[@IMSAIGuy]

I did not have the correct diode when I first built the kit, I used an SOT23 part wedged in. you can see the correct diode at 7:11

[@lancegcohen]

What is j4 on this diagram board?

[@stevenchiverton48]

is there any limit to what megahertz crystqls you can test and cant test with this circuit at least cover these details so we all know

[@alnoorratansi9364]

Hi Great video, Can you test 32khz watch crystal with this circuit ?

[@IMSAIGuy]

no.

[@estebanbriceno1625]

What transistor used for the circuit?

[@dziekan_tek]

You can use BC547 or something similar like 2N2222, as most of those small transistors works up to 200 MHz or so :-)

[@charlescartwright6367]

Trying to order the boards just isn't worth an hour wait for an engineer's review, I question pcbway's handling of existing boards they have produced... I would like to have it but their order page isn't worth it.

[@stevenchiverton48]

datesheets for the 2n3904 and 2n2222 indicate they have the same pinouts and i dont have the 2n2222 so i used the 2n3904 you said can be used, and it wont test a 20 mhz crystal nor the 100mhz crystal and you didnt say how much mhz crystals this circuit can test , and what about the voltage you didnt list that either how much voltage dose the circiut need i tried 5 and 9 volts dc and it wont work for the 20 mhz nor 100 mhz crystals

[@洪一君]

32.768KHZ can be testes?

[@IMSAIGuy]

no

[@IMSAIGuy]

kzbin.info/www/bejne/oKq9gpeQe5t-f6c

[@stevenchiverton48]

can it test a 100 mhz crystal

[@IMSAIGuy]

no, that would be harmonic type of crystal.

[@arifyulisetyawan5800]

Can it test 24 mhz xtal?

[@SpeccyMan]

MHz

[@BruceNitroxpro]

Why not offer a pure sine wave output and an "exact frequency" output rather than a "good xtal" output? That would be a better design to build. KQ2E

[@argcargv]

Do you have a good idea for the design of a clean xtal oscillator that can work at any arbitrary frequency xtal? I would think that any oscillator design that could work with a wide range of xtal frequencies would probably have high harmonic content in its signal and not have excellent frequency stability.

[@BruceNitroxpro]

@@argcargv , Again, good thinking. Perhaps a few similar designs with stability and wave shape a factor.

[@IMSAIGuy]

I hope this simple xtal tester encourages you to go and build something that is 'better' for you. This is is the best for me.

[@BruceNitroxpro]

@@IMSAIGuy , Thank you for the read and reply, and I believe we'll have some fun making like I have money AND brains LOL Just kidding!

[@robertocastaneda2634]

I want to buy this device to you

[@IMSAIGuy]

in the description

[@standishgeezer]

Anyone have any ideas for a circuit which will test low value crystals (e.g the ubiquitous 32.768 KHz) ?

[@IMSAIGuy]

I would use a simple TTL inverter oscillator circuit. you could still use the peak detector and LED part of this circuit, after the inverter darcy.rsgc.on.ca/ACES/TEI3M/Challenges/PierceOscillator.html

[@standishgeezer]

@@IMSAIGuy Thanks!

[@davidholman2536]

There’s a first - a shack desk without a single callsign label or sign. 73 de M0YDH

[@IMSAIGuy]

I know my callsign. I don't see to read it. 😎

[@davidholman2536]

@@IMSAIGuy I respect your privacy, But it is unusal in the hobby. In my defence I appear on digital amateur TV e.g. on QO-100 so have to have a callsign on the screen. Great videos and insight.

[@jdmccorful]

I order this one, will give it a go. BTW,your usural good work. Thanks!