Nice little circuit Rick. I've built similar ones using the commonly available 1Mhz crystal oscillator 4 pin cans before, but I like your design much better. :)
Hi, for the 10mh RFC in the coplitts oscillator, did you buy it or made it yourself. Its seems you need a lot of turns (around 100) on that toroid to achieve such inductance, i might be wrong though
Is there a video somewhere that explains how that circuit uses the crystal to oscillate? I understand the concept of the crystal, but I've never understood the feedback path that led to it oscillating.
@@AllAmericanFiveRadio All the components are obvious in isolation, I've understood them for 40+ years. It's how they are working together that is a mystery. The crystal is resonating at a particular frequency if it's fed an appropriate signal. The signal seems to be coming from the emitter of the transister through those two 170pF caps. There is also the 68pF cap and the 10mH inductor playing some role. Are there any of these parts we could remove and still have it work? (Ie, muntzing it).
My first plain was to put the antenna on the coil closest to the tap. The RF was at the other end of the coil, so I moved the antenna to the other end of the coil. So I do not think you need the tap. Thanks for your comment.
It is not 10 microhenry but 10 MILLI Henry. To get an idea: you can see it in the picture on 2.29 in the video. It is the one with the yellow core. When you want to make it in the same way as Richard did, also use/find such a yellow core ferrite (round) because its inductance, in this case, is related to the ferromagnetic properties of that core. Yellow stands for a certain type of ferrite material, with certain properties. It is a choke coil. When you want to make it on a cylindrical ferrite rod of 1 cm diameter, length 5 cm, you can do that experimentally. Start with 200 windings. When that does not work, make more windings on the coil. Till it works OK.
RFC coils are not critical and 10mH is just a nice round value here. Two or three dozen turns around a small ferrite toroid will do, as you can see just above the crystal in the video at 2:48. But you can buy these for cheap.
A ( good ? ) use for Medium Wavebands ( ? ) ... now that the ( BIG boys ) have almost fully shut down their transmitters due to their HUGE power needs ( welcome back to young boy's communication in the 1960's ) ... DAVE™🛑
Nice little circuit Rick. I've built similar ones using the commonly available 1Mhz crystal oscillator 4 pin cans before, but I like your design much better. :)
Thanks Doug! I'm going to do some more experimenting on this circuit.
Nice circuit. Just what I need. I always think about the scientists and engineers who made radio possible all those years ago.
Thank you. I'm going to do some more experimenting on this circuit.
What an amazing design, great Rick 👏 I will try to make this Am transmitter
Thank you. I'm going to do some more experimenting on this circuit.
Great little circuit! Thanks Rick for sharing it with us.
Thank you, and you are welcome!
Good thing they requested 1 MHz, as any other crystal frequency under 2 MHz is quite uncommon.
Nice use of the silver mica capacitors also.
Thank You!
Very nice design, I'll need to build one!
Thank you. I'm going to do some more experimenting on this circuit.
@@AllAmericanFiveRadio I ordered all the parts today. The 1Mhz crystal was hard to source. I look forward to your updates.
Hi rick, a great circuit design , on the tank circuit does the 56 to 460pf variable capacitor allow full tuning of the AM band.
The tank ciruit can be tuned over most of the AN band. In this circuit you can change the frenuency a few cycles because for the Crystal.
Hi, for the 10mh RFC in the coplitts oscillator, did you buy it or made it yourself. Its seems you need a lot of turns (around 100) on that toroid to achieve such inductance, i might be wrong though
I bought it and that is what it measures.
Thank you for sharing this design. It would be nice to have a kit and proper instructions like it was a kit put together by Heathkit.
Thank you. I'm going to do some more experimenting on this circuit.
Your bench is nice & neat like mine. My boss told me it looks like a week's laundry.
Maybe a month of laundry. Thanks.
Is there a video somewhere that explains how that circuit uses the crystal to oscillate? I understand the concept of the crystal, but I've never understood the feedback path that led to it oscillating.
The Crystal produces the signal. The transistor amplifies this signal.
Crystal Oscillators for the Beginner
th-cam.com/video/xezzwJAZEQY/w-d-xo.html
@@AllAmericanFiveRadio thank you. I've just watched the suggested video. But it doesn't explain why the circuit works.
@@ericthecyclist The quartz crystal vibrates which produces the electronic signal. The transistor amplifies this signal.
@@AllAmericanFiveRadio All the components are obvious in isolation, I've understood them for 40+ years. It's how they are working together that is a mystery. The crystal is resonating at a particular frequency if it's fed an appropriate signal. The signal seems to be coming from the emitter of the transister through those two 170pF caps. There is also the 68pF cap and the 10mH inductor playing some role. Are there any of these parts we could remove and still have it work? (Ie, muntzing it).
@@ericthecyclist I have setup just the crystal oscillator. I’ll do a video on taking out or shorting out a few components. I’ll send you the link.
Maximum undistorted modulation depth is...?
About 50% If you want more, change the bias.
What is the dia of that empty medicines bottle you wound the coil on? The bottle is tapered towards the bottom edge, so ...
The coil is wound on a pill bottle. The diameter is 1.25 inches. I’ll put this information in the show more of this video, thanks!
@@AllAmericanFiveRadio cool sir
@@awaismushtaq5719 Thank you, and you are welcome!
Why the tap on the last coil?
These taps on the resonant circuits are used everywhere explained nowhere.
@@OmarBenjumea I dont think so. It forms an autotransformer. But for what purpose, I do not know.
@@sahhaf1234 Looks like it steps up the voltage some and also may provide a better match to the antenna.
@@radiofun232 I dont have an oscilloscope, can you pls explain to me what I am supposed to see? Is it related to bamdwidth (ie, the Q factor)?
My first plain was to put the antenna on the coil closest to the tap. The RF was at the other end of the coil, so I moved the antenna to the other end of the coil. So I do not think you need the tap. Thanks for your comment.
@@AllAmericanFiveRadio Thanks,
thank you. i appreciate you. take care.
Thank you. I'm going to do some more experimenting on this circuit.
Good show!
Thank you. I'm going to do some more experimenting on this circuit.
👌
Thank you, and you are welcome.
The inductive coil with a value of 10 microhenry, what are its specifications?
What is its diameter?
And how many turns?
It is not 10 microhenry but 10 MILLI Henry. To get an idea: you can see it in the picture on 2.29 in the video. It is the one with the yellow core. When you want to make it in the same way as Richard did, also use/find such a yellow core ferrite (round) because its inductance, in this case, is related to the ferromagnetic properties of that core. Yellow stands for a certain type of ferrite material, with certain properties. It is a choke coil. When you want to make it on a cylindrical ferrite rod of 1 cm diameter, length 5 cm, you can do that experimentally. Start with 200 windings. When that does not work, make more windings on the coil. Till it works OK.
RFC coils are not critical and 10mH is just a nice round value here. Two or three dozen turns around a small ferrite toroid will do, as you can see just above the crystal in the video at 2:48. But you can buy these for cheap.
@@radiofun232
Thanks.
@@Bob-1802
Thanks.
I bought mine on eBay. Thank You.
This is good because I am getting used to using MOSFET's these day's.
Thanks! Keep experimenting!!!
love it
Thank You!
Nice circuit ...73
Thank you, and you are welcome. 73
A ( good ? ) use for Medium Wavebands ( ? ) ... now that the ( BIG boys ) have almost fully shut down their transmitters due to their HUGE power needs ( welcome back to young boy's communication in the 1960's ) ... DAVE™🛑
Thank you. I'm going to do some more experimenting on this circuit.
Very Good Sir! Best Regard Matthias,Keine Funken am Drehkondensator?¿❤😂🎉😊
Thank you. I'm going to do some more experimenting on this circuit.