MOSFET AM Transmitter Home Made Oscillator Coil PART II

[@OIE82]

Gonna have to build this one. After watching "AM Transmitter Build Project and Demo" from 5 yrs ago, I looked to order a PRC-070-OSC. $70.00 on Ebay! So I was happy to see that you had updated the circuit for a DIY coil. It may be the microphone but I think this is the best sounding transmitter you have done. Imperfect carrier wave and all! 😉 And it beats the amazon transmitters I have tried. Thanks again.

[@AllAmericanFiveRadio]

Yes I was surprised to see the price of that coil. Let me know what happens! Thank you!

[@RestoreOldRadios]

Rick - great job on the new coil and circuit modifications. I love how you showed the signal flow. One trick I’ve used to cleanup the sine wave is to place an RF choke (inductor) of 180 uH or greater just before the 500 pF capacitor dependent on your wire antenna length. Thanks again for sharing your design and theory of operation. Best, Don

[@AllAmericanFiveRadio]

Hey Don, Thanks, and thanks for the sine wave cleanup tip. I have done this circuit before, maybe ten years ago. But I did not explain how the circuit works. If you change the tank circuit you can get it on the FM band and even on the two meter band and more. This is a fun and cheep circuit to learn with and can be very useful. Thanks again Don. Rick

[@roncaruso931]

Nice little circuit. I understand the electronic theory of AM, FM and TV. It still amazes me that we are sending audio and video through the air!

[@AllAmericanFiveRadio]

Yes it is! Thank you and your welcome.

[@stanmeyer9770]

I always find it fascinating how complex so many of these AM transmitter designs are posted on KZbin that actually have very little range and sound quality, yet a simple one transistor oscillator does the job as well if not better. My first experience with a AM transmitter was building a one transistor transmitter in the early 1970's it was based on an OC44 transistor and the coil was wound on a loop stick about 15cm long. The coil consisted of 3 sections the tank winding, a feedback winding and the audio input winding that was modulated by a germanium diode via the audio input connection which was designed to work off a carbon mic. We tossed the mic and replaced the input with the output of a tape recorder external speaker connection and modulated the transmitter that way either with play back music or the tape microphone set on record and the pause button to transmit vox. My friend who lived down the rd about 800m away from me had the same system and we would communicate to each other as a fun experimental project. The reason that this circuit attained that range was due to the use of the tape recorders amplifier ( standard 4 transistor 9v) and the fact that the coil was wound on a long ferrite rod ( standard radio type loop sick) and by adding and external wire anntena 10m long that was strung to a tree outside and connected to the transmitter by winding about 5 turns onto the loop stick and connected to the ground terminal of the circuit in this case the positive supply rail. Thanks for the simple design you have posted and keep tweeking to improve your results.

[@audioal8015]

Rick that sounds amazing, great sound produced from that little TX .

[@AllAmericanFiveRadio]

Thank you.

[@nonamex3052]

Really nice. I really appreciate the coil simplification. Usually this part of the circuit on good am transmitters is very discouraging

[@AllAmericanFiveRadio]

Thank you.

[@JorgeMartinez-py7wb]

Hello Rick, could you please explain how do you define the values of the capacitors, how did you tune the frequency and in general a bit of the theory behind the design in more depth. Your videos are very educational and I have always thought that there is a gap in the modern way electronics is thought between theory and practice. It's very nice you share your knowledge to close that gap. thank you.

[@AllAmericanFiveRadio]

THANK YOU.I'LL BE GALD TO SOMETIME SOON, BUT UNTILL THEN HERE IS INFORMATION THAT MAY HELP. Oscillators, the Basic Tank Circuit 1 kzbin.info/www/bejne/nIKXqoWMet-Lh6M AM Transmitter Tank Circuit Coil Capacitor Resonance kzbin.info/www/bejne/bIW1ooGhiZqCec0

[@hamzahkitech5228]

I have made this Am transmitter, i wound coil on ferrite core and used mosfet IRF 630 and got great result sound quality is really amazing

[@AllAmericanFiveRadio]

That is a GREAT IDEA!!! If you do a video on your transmitter showing how will it works, I’ll put a link to it in the SHOWMORE of this video. Thank you!!!

[@hamzahkitech5228]

@@AllAmericanFiveRadio Yes I was thinking about to make video about it , I will definitely make it when I get some time , in short I used same circuit as yours except I put voltage divider network of 10k on both sides as you did in older videos of Am Tx , I used IRF630 and feedback capacitor was 2.2nf , coil is ferrite core of 75turns total turns 60turns+15turns between 60 and 15turns I take tapping of coil connected to positive side , I used 560 ohm of 1/2 watt resistor because I did not have 500 ohm resistor.This is all what I did, the sound quality is excellent, I will put earth and antenna to test how much far it can go, thanks for giving this design on KZbin, it is because of you that I am able to make this successful transmitter, again thanks a lot.

[@edtully2740]

My build worked perfect after I obtained a good variable capacitor. Thank you for the learning experiences! Next goal is to get the FM transmitter working (I haven't had any luck getting this one to oscillate in the appropriate band yet).

[@AllAmericanFiveRadio]

Glad you got the AM transmitter working. You may have found my newest FM transmitter video. Just in case I’ll put the link below. It surprised me how well it worked. If you have questions do not hesitate to ask! Thanks you! FM Transmitter Home made Coil Build Demo kzbin.info/www/bejne/f6qbg6KiZtOMY6s

[@edtully2740]

I made a hardwired version of this transmitter, which I can use for my AM radio repairs.

[@AllAmericanFiveRadio]

@@edtully2740 You should find the AM transmitter useful in your repairs. You will have fun just playing OTR also.

[@russedmonds227]

Very nice circuit. It would be nice to see the audio modulation on the oscilloscope by changing the time/division setting.

[@AllAmericanFiveRadio]

The modulation looks normal. Thank you!

[@romjone4801]

Great circuit! Can you use an MPF102 fet? Also, did you check the harmonics?

[@AllAmericanFiveRadio]

Yes I have used an NPN transistor. You may need to change the bias.

[@faridsafazadeh1137]

Hi Rick, Thank you so much for great clips. I have a question. Where do you buy those elctrolitic capacitors(those yellow ones). You know I buy everything from Aliexpress but the caps from there not so great. Please kindly let me know where is your sources to buy your electronic parts and supplies... Thanks again.

[@AllAmericanFiveRadio]

Thanks! I’m sure you can get then from Mouser Electronics and or DigiKey. I got these capacitors from Antique Eletronic Supply: www.tubesandmore.com/

[@drtidrow]

Gotta love classic radio shows. 🙂

[@AllAmericanFiveRadio]

Thanks.

[@betopx2]

congratulations... This circuit works with 24 volts to have more power?

[@AllAmericanFiveRadio]

Thank you. Yes it will, but don't tell anybody.

[@macgvrs]

I think I need to try that. The range would be better than the transmitter I now have.

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@sobhisaad1382]

Hello Rick How are you ? Can you please explain how did you build the oscillator Thank you

[@AllAmericanFiveRadio]

The oscillator is a positive feedback circuit. I make a video on how I made the coil. COIL kzbin.info/www/bejne/n3iuhoCagL9qirs

[@sobhisaad1382]

@@AllAmericanFiveRadio thank you so much

[@AllAmericanFiveRadio]

@@sobhisaad1382 I added the COIL video link in the SHOW MORE of this video. Thank you, and your welcome.

[@overengineeredinoz7683]

Great breakdown of how it works

[@AllAmericanFiveRadio]

Thank you.

[@garygranato9164]

great vid , please tell me what the 500pF cap after the antenna does ??

[@TriodesPs111]

it looks to me like its to keep DC off the antenna so if the antenna makes contact with something grounded it wont dump the DC power from the circuit to ground. and since we are putting out RF and not AC audio, the cap value doesn't need to be very high to let the signal through but block the DC. so just 500pF was sufficient.

[@garygranato9164]

@@TriodesPs111 cheers

[@AllAmericanFiveRadio]

Yes, only RF on the antenna.

[@larslande]

Interesting, but what is the range of this thing, and how should the antenna be for maximum range? Can you experiment on how to make an amplifier stage and filter, and also connect an matching antenna?

[@AllAmericanFiveRadio]

It will cover two to three rooms. With a small antenna it may cover the whole house and more.

[@larslande]

It remindes my of an ordinary FM oscillator circuit, but you have made a feedback to make it oscillate better as needed at lower freuencies. Now we need to make an amplifier stage, filter stage to 50 Ohm cable and making a rod antenna with incuctor at bottom. 10W should do :)@@AllAmericanFiveRadio

[@xXTheoLinuxXx]

@@larslande a filter and/or antenne matcher is easy to do, but the 10 watt requires a bit more work :) This transmitter with one mosfet is an oscillater but als a modulator. So with 10 watts you need a seperate modulator. The 'old' rule is that you need at least 50% modulation, and that isn't something this would provide. Sure it can be done based on this transmitter with a few buffers and a IRF510 (which provide around 16 watt PEP), but that would be something different than this (building a small but good transmitter with just a few components).

[@sobhisaad1382]

Hello Rick How are you? and sorry for disturb Do you have any circuit about an AM transmitter using crystal oscillator Hope you help me and thank you

[@AllAmericanFiveRadio]

No not a transmitter, I do have a video on a crystal oscillator. What frequency are you wanting to broadcast on? Heres the link to the crystal oscillator video. Oscillators for the Beginner kzbin.info/www/bejne/rpbdq6qAdr94h7sal

[@sobhisaad1382]

@@AllAmericanFiveRadiothank you for helping Mr Rick the frequency that I want is 1MHZ and then I will look for the AM modulator circuit appropriate for this oscillator

[@AllAmericanFiveRadio]

@@sobhisaad1382 I think that would make an interesting project and video, thanks. I'll see about ordering some 1MHz crystals.

[@AllAmericanFiveRadio]

@@sobhisaad1382 I completed my last video. I just ordered a 1MHz oscillator IC for the transmitter project. Should be an interesting build and project.

[@AllAmericanFiveRadio]

I got the IMHz oscillators and they are accurate, but they are square wave, not mentioned on the eBay site. So I just ordered some 1000KHz crystals. I could use the other oscillators, but the filtering weakens the signal to much to be useful.

[@DERB_Seymour_Indiana]

Sounds pretty good Rick. What's the range on it? That always seems to be the difficult part of the ones we have experimented with. :)

[@AllAmericanFiveRadio]

Hey Doug, it will cover two or three rooms with two alligator clips as an antenna. With more power and a good antenna it should cover the house and more.

[@RadioFixer]

Hi Rick, this is awesome 👏👏 you are amazing. This is very very helpful for us. What is the range for this AM transmitter? It sounds much much better then “Talking House”. Thank you for making these videos. Have a great day Rick! Regards, Jay

[@AllAmericanFiveRadio]

Hey Jay, it will cover two or three rooms with two alligator clips as an antenna. With more power and a good antenna it should cover the house and more.

[@RadioFixer]

Rick, can I increase the power to 18 volts DC or that will damage the unit? Thank you very much. You are genius.

[@AllAmericanFiveRadio]

@@RadioFixer Hey Jay, this circuit should handle 24VDC. You'll have to increase the audio input because the DC bias increases.

[@paulsto6516]

I enjoyed that! Thanks.

[@AllAmericanFiveRadio]

Thank you and your welcome.

[@Pilotfly2023]

Very good... Thks, friend!

[@AllAmericanFiveRadio]

Thank you and your welcome.

[@attilarivera]

Very interresting ...

[@AllAmericanFiveRadio]

thank you.

[@Tosicam_offical]

hi,can you help us do a review on youtube

[@AllAmericanFiveRadio]

I maybe able to help.

[@dwtees]

Rick are your high resolution wiring diagrams and schematic still avaliable for your Build a "AM Transmitter, Project"?? Can I give you my email address here??

[@AllAmericanFiveRadio]

You can use my email. [e-mail]