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I think the capacitors on the schematic are not labeled in a consistent way. I think sometimes we are supposed to assume pF and other times we are to assume uF. This is terrible for newbies. I t

😂 Too simple I made a 4 transistor circuit that has 2 oscillators: one modulating a multivibrator. It has several adjustable parameters so you can generate sirens, tones strange wobbling/shimmering sounds. Its supplied by an LM7812, uses a rechargeable 22V battery from a vacuum cleaner which directly supplies a TDA2050 audio power amp IC. A momentary switch "the black button" feeds the audio from the generator circuit to the power amp via a potentiometer to control volume. Zero to 15W. Its all built into a steel lunch box. I feed a 30W 8ohm horn speaker with it. Great for a practical joke. You walk around with the speaker in a bag making ear ringing short bursts and watch people 😂

Nice

Why tease us with glorious images of Radio Shack 150-In-1 project kits and such if you’re not going to talk about them?! LOL! 😂😂😂

Greetings from Australia! Thank you very much for another fascinating video. Your videos are always immensely interesting and take me back to the Golden Age of radio and electronics. Your channel is definitely one of my favourites. Thank you, Sir. And may you produce many more.

Heh cool, now we use a few billiion transistors (mictrocontroller) to make an oscillator wih a simpe line of code. I loaded up a saw wave example code on my stm32 and sure enough it puts out a nice saw wave at 200khz. $1 in parts, 0 soldering. But i didnt learn anything... another copy and paste and I had a white noise generator, sounded just like it too. Copy and paste is so much easier then wiring up an new circuit... but you dont learn anything.

I have a key just like the one you have in the video. My dad was a ham for a great many years and did cw all the time. When he passed away, I fortunately got to take his key home with me. I remember watching and listening when he was on the air. My brother who is also a ham, has dad's QSL cards up on his wall in his shack. Sooo many memories of all those years sitting the shack with the both of them making contacts all over the world !!!

Came to see because of the thumbnail. Left disappointed. 😑

👍Thanks for videos Mike. At one point I think you said that you "cloojed" the capacitors around the switch. I have never heard this term before. I made few simple practice oscillators in the past. The one thing I always had trouble with was annoying key clicks.

Thank you! de SA3BOW

I liked the explanation round the Hartley oscillator and am looking forward to the next instalment. 👍😃

Muy bueno, quiero hacer uno tipo walkie con cristales 28,800. Gracias por su trabajo y buen proyecto, 73 de Toni, EA5HYW.

It's nice to have a bit of chirp going on, it gives it a bit of character that a pure sine wave just can't even come close to. Maybe less regulation in the power supply would be worth a try.

FOR WHAT YOUR DOING ON THIS VIDEO IS WHY I LIKE THE AMATEUR RADIO HOBBY, NOW I AM PASSING THE KNOWLEDGE AND HOBBY TO MY SON , it’s another link in life . Thanks for your time to teach you are a true AMATEUR RADIO OPERATOR 👋👍

When you show the schematic for the Hartley "conversion", you drew it in green, are you also meaning to use that green line to put the whole value of the potentiometer from the ckt to ground?

I have been watching your videos (and Mr. Carlson's Lab) for years now and I am always anxious to see the next one. Kind of like waiting for the next issue of 73 magazine! Thanks!

Great video! Thanks!

Thanks Mike. Great video with lots of theory. When I was 7 or 8 my parents bought me the Transistor Radio & Broadcast System you show in the outro. Remco brand. That set probably more than anything else got me hooked on electronics.

Thanks Mike. 73's🎙KD9OAM🎧📻📡 🚧

Great video! Thanks for making this interesting and entertaining. I enjoyed seeing the 1960-70's pictures.

Well, if you're covering the greatest receivers of that time, the "Big 3" of the 50's and early 60's were the R-390/392, The National HRO-50/60 and the Hammerlund Super Pro 600. Nothing ever came close. and...there WERE repairable surplus examples for (somewhat) affordable prices....I'm glad you mentioned the HRO 500 and Hammerlund 180. I had both and with the right antenna top sides they were Suprr World Class.....I had the TMC's sort of a mil spec off brand which had a sort of cult around it. A lot of guys endlessly modified their receivers for at times far better performance. It was a wonderful time of learning experiences......

When I was some where around 9-12 years, I seen this same "Transistor Radio & Broadcast System Kit". I remember it look identical to the Radio Shack 60-2276, pictured at end of this pt2 video, but it was in a Wards Airline catalog. I want one, but my parents didn't have the money.

This is great! Do you plan on doing a valve version?

Man I would kill for a good 70's transceiver. I wish more radios stopped using LCD's and actually went back to basics.

Why did you name the capacitor after you? (one mike). Instead of a transistor why not use a 4CX5000 tube?? It would be louder. Instead of a J-38 key you could have used an old house key?

Awesome!!!👏👏👏👏

Why 60 kHz? I get that it's well over 3x the highest audio frequency we're likely to see, but most other PWM transmitters I've seen use frequencies like 175 kHz for the sawtooth....my guess was to make it eaiser to filter out any noise from it on the output (you mentioned earlier if you don't filter it out you get spurious sidebands...)

Thanks! I just came across this. I want to build a low-power transmitter for the AM broadcast band to provide "content" for my collection of AM radios, and I think one of these PDM/PWM designs based on the TL494 would be perfect.

To complicated! The one that I built years ago was extremely simple, used a single 555 IC, and was featured in the first few pages of an ARRL handbook, maybe about 1969. It featured volume and tone controls and required a single 9-volt battery. All of the components used would still be available today for purchase. Just wished I had that schematic.

my favourite crystal radio is a shortwave set, back in the 1980s I got loads of Soviet propaganda on it, Thankfully not much of that now.

My first radio was much simple, you just need a radio antenna a germanium diode EFD 108,a speaker(2000 ohm impedance) from a old phone with carousel dial, a ground connection and you can listen AM local radio station no battery needed.

Hi Mike, on the subject of simple projects, I'm building a whole bunch of Paraset portable 12v PSU's. A little birdy says you might need one?

what about using two SSB modulators and a limiter you know you use one SSB as the modulator driving a limiter then back into the second SSB modulator operating as a demodulator should sort any muck and get some clean modulation.

"Enjoy your day, and let nobody steal your joy.". Sage Advise.

If this is a kit, I will buy one.

I built a single transistor code practice oscillator in 1969 while in Vietnam working on a Novice license. I got to 5 wpm, but gave up when sent to another command, thanks for this one Mike. 73's🎙KD9OAM🎧📻

Charlie W.

Super cool video!

, Who invented Morse code?

Viewer suggestion: go to all those rallies and buy all the old TRANSISTOR circuit books you can find. ICs come and go. Most transistor circuits, even 60 years old, can still be made to work without much effort.

This was fascinating and so well explained. Thanks Mike. Have you ever used the later Si 4732 and Si47xx series of chips?

"But Mike! Where do we buy the kit of parts?"

Unfortunately, I have a bad habit of looking at all the old transistor radios I find and instead of snatching useful parts from them I think, "I bet I can fix this thing. It's probably just a bad connector or a shorted cap. And even if it's a transistor, I have bins full of them. Sure the tuning cap would be good in a QRP antenna tuner, but this cool old radio is already all here and just needs to be fixed. Besides, I already have a QRP antenna tuner, 2 of them in fact. A little super glue will fix this case just fine and I can stick in a little step-up inverter module, shield it with aluminum foil since this is an AM radio, add a few filter caps and an inductor to quiet it down, and a lithium battery pack to drive it all instead of those 4 old C cells. Probably run for days, especially if I put a small solar panel on top. And I think I have a longer-throw speaker this size somewhere, too. This thing could sound great by the time I'm done with it! And I could listen to it when I'm working out in the shed instead of listening to the 4 channel 400 Watt SONY Dolby system I have in there already."

Could you gives us some close ups of those cool old books you showed briefly in the intro ?

Robert Moog would be proud! So happens that I went though my junk box the other day and found a metal can germanium transistor with a whopping hfe of 42! I've heard that germanium (not geranium) components are heat sensitive to soldering the leads too close. I enjoy ALL of your projects, even when they're way too complicated for me. As it stands, I need to build your noise antenna because I haven't been on the air much since April when we had a power outage and the neighbor's house 500 ft down the road switch mode power supply decided to be an incredible S9 noise maker after we had a power surge when the power came back after we had 30 inches of snow around Easter. Terrible TOROIDS are in my future, but I have found some pretty cheap. Thanks for all you do! You always have excellent content well put together on this channel. 73-W1RMD.

I really don't condone scrapping an old relic of the past like that. Repair that old transistor radio and get the parts somewhere else instead. But that's just me. To each their own I guess. Good video anyway. Thanks and keep up the good work.

Right then. That's my girlfriends evening planned out then.

❤❤❤❤❤

This is a good video. Keep them coming

This was an absolutely wonderful presentation and answered questions about D-Day communications that I didn't even know I had. My Dad went ashore on D-Day plus three and I'm sure that this equipment kept him and other GIs so much safer in their advance on Normandy.