It serves better as a low power oscillator in a receiver circuit, allowing reception of SSB morse. For an emergency SOS TX a good old spark gap setup will certainly get out more signal.

​@@zinckensteelSSB Morse?

How that would go: Prof. would connect it all up, make sure it was all connected properly, and then go off to get the coconuts to make the batteries out of; meanwhile, Gilligan would cluelessly disconnect part of the antenna wire to use as a laundry clothesline. Not enough to make it completely inoperable, but enough so that the signal wouldn't reach beyond the island, leaving Prof. to wonder why no one ever responded to their SOS. And of course he'd never think to RE-check the connections he'd already checked. By the next episode the whole thing would've been forgotten :P

@@bledlbledlbledl Exactly

@@DeeegerD I think he means to use it as a BFO (Beat Frequency Oscillator), to inject a signal into a receiver IF at the IF frequency itself. This lets you "decode" USB and LSB as well as it'll put a tone in your receiver when someone is using pure CW. If your receiver has a 455kc IF, you'd need a 455kc crystal, for example. It would definitely work for that.

Yes, finding negative resistance spots can be time-consuming. On some plates, I found more active spots. It is easy to find them if you have a radio nearby that is tuned to the frequency of the crystal. You will hear short clicks and beeps as you adjust the cat-whisker. Finding stable ones can still be tricky.

@@ashishderhgawen I was comparing the samples of natural zincite to fresh burned zinc-on-steel; the latter is much easier to get running in such a circuit. I used both an oscillator circuit to test as well as a curve tracer - this material gives a bidirectional Z-shaped curve, whereas a classic tunnel diode has a unidirectional N-shaped curve

@@zinckensteel I can't get zincite here. That's interesting. You should record a video of the curve tracer output. I'd love to see it. I don't have a curve tracer, but I've been able to use my signal generator and oscilloscope to get a glimpse of the curve. The problem is I struggle to find a stable spot on the zinc when trying to capture the trace. I see it for a split second when adjusting the catwhisker, and then it is gone.

@@ashishderhgawen I have some still images taken a while back that I could send to you, or figure out how to incorporate into a video for easy sharing. The setup was similar to yours but I used a 60Hz step-down transformer to provide the bias sweep. I found that a brush of copper wool or a small pack of the finest stranded wire you can find makes a more reliable cat's whisker "point" in this case. The resulting effect is likely the result of multiple impedances in parallel, some of the desired negative resistance, most more like a TVS diode if not ordinary resistance.

@@zinckensteel I like the idea of using stranded wire. I will try that out.

Zinc-plate on steel...aka galvanized steel.

@@pirobot668beta oh thanks

I don't know how fast this can go. I've used this as an oscillator from about 200 Hz to 7 MHz. Haven't tried going beyond that yet.

Differential negative resistance shows up in many materials under various conditions, and the speed can vary wildly as the physical process behind the effect can also vary greatly. In other words, it is unlikely to be anywhere near as fast as a classic tunnel diode.

It's a 4 MHz crystal. It's finicky but it can run continuously if you find a stable spot with the cat-whisker.

@ashishderhgawen Ok thank you.

I'm using #30 AWG copper wire for the whisker. Black spots on the zinc are good places to find negative resistance. Finding stable oscillations can be tricky. Good luck! If you are using a crystal, you can tune a radio to the crystal's frequency and keep it nearby. That's the easiest way to know when the oscillator is working.

This works well with steel. I often use a phonograp needle mounted on the end of a small flat spring. There are videos on my channel.

I will try adding modulation to this. That would be interesting

with the right FM deviation an AM receiver would demodulate it as if it was AM

Yes, this should also work with an LC circuit. I haven't tried it yet. I will give it a shot!

@@ashishderhgawen okay thanks for replying! Nice, I'll keep an eye on it and watch with interest! healthy and friendly greetings from Rotterdam location! RadioRob

@@hobbyrob313 I tried it today. For the inductor, I used the 110V side of a 110V-12V transformer. I connected a 0.22uF capacitor in series. So, the inductor and capacitor are parallel to the zinc plate/cat-whisker. It wasn't easy to get it to oscillate. After trying for 20 minutes, I finally managed to get stable oscillations. It was oscillating at about 200 Hz (in the audible range). I tried connecting a speaker on the other side of the transformer, but it was too much load for the zinc oscillator. A high-impedance speaker would have worked. I could add a variable capacitor and then adjust the frequency.

@@ashishderhgawen Low frequency operation has always been strangely less stable than HF in my experience.

That works well . I mainly tried the LCs at low frequency. There are videos on my channel.

Yeah, but the 795mV is just the open circuit RMS voltage from the unloaded oscillator. It's not going into a 50 ohm load. When it is loaded, it would be even less power. But low power signals can still travel far. I've seen Nyle Steiner use a similar zinc transmitter to send a signal 5 miles away!