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. :)
I mean no disrespect by asking this. Are you sure the yellow inductor is 10 milli Henry? I ask because the yellow core of the choke looks like a T50-6 core, and you can't wind enough turns of even fine enamelled copper wire around such a core to get even close to 10 mH and the wire you have used is much thicker than I have tried to use. A 10 mH choke is a huge choke both physically and RF wise too. May I ask what the core is that you used for the oscillator collector choke and how many turns of what diameter wire you used to achieve 10 mH, please? I hope to build this TX, but the oscillator is a problem because of this collector choke being such a large value and not being able to find a core suitable to achieve 10 mH, I have tried T50-6, T25-6, and T44-6 cores, all of which I can not wind enough enamalled copper wire on to in order to achieve 10 mH inductance. To know what core, wire and how many turns you used, would be a huge help. Thank you, KW.
You are right. Somehow I missed remembered by 100X. I just re-measured the coil and it reads 0.10mH. I have put this information in the SHOWMORE of this video. You use to be able to put this in an uploaded video, but do to another UA-cam improvement you cannot any longer. Thanks for pointing this error out to me. If you have any other question please contact me, I’ll be glad to try and help.
Wow, thanks to tank circuit I can finaly adjust the output frequency a littlebit Was wondering does a store bought 4pin crystal oscilator have any advantages over this Colpitts oscillator u have built? Also how does more voltage help? If u use more voltage, will the signal be stronger? Also whats the minimum and maximum voltage I can use? Is this determined by the crystal or by sorounding components (I gues I would need to adjust the value of a capacitors, resistors and use a different transistor if I want to use a different voltage)
The 4pin crystal oscillator puts out a square wave; a video on this is below. I think this circuit should work from 15VDC to about 30VDC, and yes a higher voltage would produce more RF output. To get more power out you need to change out the MOSFET bias and change the 500 Ohm resistor. MCO 1510A 1MHz Oscillator Square Wave to Sine Wave ua-cam.com/video/2rvFYVHMnpU/v-deo.html
@@AllAmericanFiveRadio thnx Why do u need a mosfet anyway? I thought NPN tranzistor would amplify the RF signal Also how do u determine the right values for resistors and capacitors and ur choke?
@@DXingSlovenija You could use a NPN, the base bias would be between 1-3 VDC and is low impedance which can lower the signal to the base. The MOSFET gate is biased from 12-14 VDC and is very high impedance which does not load down the signal as much to the gate. The resistors for NPN bias must turn on the B E junction without shorting out the signal to the base. The MOSFET gate impedance is about 10Meg so it is easy to bias without loading down the input signal. The capacitors and choke are chosen by the frequency to be used.
@@AllAmericanFiveRadio ah so if I understand this corecly, if I use the mosfet I will have higher output signal then if I used a npn transistor on its place? PS: so the first npn transistor (2N2222) is needed for the crystal to oscilate (could I make crystal oscilate without it?) And the mosfet then amplifies the very weak output signal What about the tank circuit (is it only for there so u can change the output frequency or does it do some other function as well? (Could the transmitter work without it?) Sorry for stupid questions, just trying to understand this interesting subject
@@DXingSlovenija The more of the signal you can get to the base or gate the higher the output. I never thought about using a MOSFET in the crystal oscillator circuit, I’ll give that a try, interesting idea. The tank circuit helps make a nice sine wave. The tank circuit also acts as a RF Coke, it keep the RF output from going into the power supply and keeps it out on the antenna. Keep asking your questions.
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.
Great little circuit! Thanks Rick for sharing it with us.
Thank you, and you are welcome!
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.
I mean no disrespect by asking this. Are you sure the yellow inductor is 10 milli Henry? I ask because the yellow core of the choke looks like a T50-6 core, and you can't wind enough turns of even fine enamelled copper wire around such a core to get even close to 10 mH and the wire you have used is much thicker than I have tried to use.
A 10 mH choke is a huge choke both physically and RF wise too.
May I ask what the core is that you used for the oscillator collector choke and how many turns of what diameter wire you used to achieve 10 mH, please?
I hope to build this TX, but the oscillator is a problem because of this collector choke being such a large value and not being able to find a core suitable to achieve 10 mH, I have tried T50-6, T25-6, and T44-6 cores, all of which I can not wind enough enamalled copper wire on to in order to achieve 10 mH inductance.
To know what core, wire and how many turns you used, would be a huge help.
Thank you,
KW.
You are right. Somehow I missed remembered by 100X. I just re-measured the coil and it reads 0.10mH. I have put this information in the SHOWMORE of this video. You use to be able to put this in an uploaded video, but do to another UA-cam improvement you cannot any longer. Thanks for pointing this error out to me. If you have any other question please contact me, I’ll be glad to try and help.
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.
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!
Your bench is nice & neat like mine. My boss told me it looks like a week's laundry.
Maybe a month of laundry. Thanks.
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.
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.
Wow, thanks to tank circuit I can finaly adjust the output frequency a littlebit
Was wondering does a store bought 4pin crystal oscilator have any advantages over this Colpitts oscillator u have built?
Also how does more voltage help? If u use more voltage, will the signal be stronger?
Also whats the minimum and maximum voltage I can use? Is this determined by the crystal or by sorounding components (I gues I would need to adjust the value of a capacitors, resistors and use a different transistor if I want to use a different voltage)
The 4pin crystal oscillator puts out a square wave; a video on this is below. I think this circuit should work from 15VDC to about 30VDC, and yes a higher voltage would produce more RF output. To get more power out you need to change out the MOSFET bias and change the 500 Ohm resistor.
MCO 1510A 1MHz Oscillator Square Wave to Sine Wave
ua-cam.com/video/2rvFYVHMnpU/v-deo.html
@@AllAmericanFiveRadio thnx
Why do u need a mosfet anyway?
I thought NPN tranzistor would amplify the RF signal
Also how do u determine the right values for resistors and capacitors and ur choke?
@@DXingSlovenija You could use a NPN, the base bias would be between 1-3 VDC and is low impedance which can lower the signal to the base. The MOSFET gate is biased from 12-14 VDC and is very high impedance which does not load down the signal as much to the gate. The resistors for NPN bias must turn on the B E junction without shorting out the signal to the base. The MOSFET gate impedance is about 10Meg so it is easy to bias without loading down the input signal. The capacitors and choke are chosen by the frequency to be used.
@@AllAmericanFiveRadio ah so if I understand this corecly, if I use the mosfet I will have higher output signal then if I used a npn transistor on its place?
PS: so the first npn transistor (2N2222) is needed for the crystal to oscilate (could I make crystal oscilate without it?)
And the mosfet then amplifies the very weak output signal
What about the tank circuit (is it only for there so u can change the output frequency or does it do some other function as well? (Could the transmitter work without it?)
Sorry for stupid questions, just trying to understand this interesting subject
@@DXingSlovenija The more of the signal you can get to the base or gate the higher the output. I never thought about using a MOSFET in the crystal oscillator circuit, I’ll give that a try, interesting idea. The tank circuit helps make a nice sine wave. The tank circuit also acts as a RF Coke, it keep the RF output from going into the power supply and keeps it out on the antenna. Keep asking your questions.
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.
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
ua-cam.com/video/xezzwJAZEQY/v-deo.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.
thank you. i appreciate you. take care.
Thank you. I'm going to do some more experimenting on this circuit.
Maximum undistorted modulation depth is...?
About 50% If you want more, change the bias.
👌
Thank you, and you are welcome.
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,
This is good because I am getting used to using MOSFET's these day's.
Thanks! Keep experimenting!!!
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.
Good show!
Thank you. I'm going to do some more experimenting on this circuit.
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.