Thank you Norman. I realize this video is from the way back machine, but it answered a question for me about crystal radios. I built one in about 1959 or 60 when I was 10 or 11, now I'm reliving my childhood I guess, because I decided to build one and did a few days ago. Just checking up to see if I got it right, now I need to get some alligator clips for ground and antenna.
Brilliant! I recently decided to build a SW radio from an old Archer kit schematic and bought a 365 pF varicap. Was surprised to see four terminals, not two as the smaller, plastic one in the original kit had. Attached a knob, hooked up capacitance meter probes to opposite-side terminals- no change whatsoever. Kept trying different terminals. Same damned thing. WTF?!?! Found your video via Google. I used to think that I knew something about electronics, but that's the side of me that reads Jim Williams but doesn't like dragging itself to the breadboard and doing anything *practical.* THANK YOU!!!
I enjoyed that so much thanks! I'm just getting back into amateur radio after a 30 year break and it was good to go back to basics and go through all the types of variable capacitor. You explained this simply and clearly..
Hey there! Yes - everybody seems to have these lay-offs, in order to attend to stuff like kids growing up, needing attention & guidance &c.!! But it's nice to come back to 'an old friend' hobby. Wishing you all the best with it. Take care, & best 73, Norman G4LQF, ex-WS0B.
I have been reviewing your crystal radio videos and bought a 365 pf variable cap and wound up a coil on two inch PVC with radio shack mag wire. Interesting so far I have two stations in the high end of the am like 1310 etc. Not sure what coil modification will make it tune further down the frequency range. Thanks Norman you're the man!
+area46241 Hi there - thanks for writing. just make the coil maybe twice as many turns - fasten the new end down temporarily with sellotape or insulating tape - that will get you down to a lower frequency. If it's too low, take off a few turns, until you get the widest coverage. It may not tune the whole range of the Medium Wave. However, if your 365 pF is a twin gang and you're only using one gang, put both gangs in parallel, which will give you 730 pF. You might try this before adding turns... You could also have a small fixed capacitor - say 220 pF - in parallel with your 365 pF. Tiny disc ceramic fixed capacitors are cheap & will work OK. Good luck!
Once again you did an outstanding job FB. I had always wondered what was connected to ground. I'm going to check the crystal set I built about 5 years ago to see if I did it right. I was only getting one station. Keep your videos coming I enjoy them all
I recently saw one of these in a FranLab video and hadn't seen them before. Very neat. Can't say I'm very familiar with air-gap capacitors. Makes sense that they're such low capacitance
Philips commercial 2-way FM transceivers from the 1960s were full of those beehive trimmers. They could be converted to the amateur 6 metre band. I tried it but could never get the thing to transmit consistently , but it would receive.
Thank you for your courtesy in replying! If the video was helpful to you, then it has served a purpose which exceeded my humble effort in making the video! Wishing you the very best of good fortune in your future career. Norman.
Back in the days of RADIO FREE EUROPE when the U.S. was transmitting radio into the Soviet blocked countries behind what at the time was called the iron curtain. To prevent the people that lived in the blocked countries from receiveing the U.S. broadcasts the cap had small bumps on two opposing plates that came in contact with one another shorting out the cap and preventing the osalator from osalating on that frequency and preventing the radio from receiveing the frequency that the U.S. transmitted on. Some of the people would file down the bumps so they no longer made contact so they could still receive the U.S. brodcasts. I don't I don't know if there was a penalty if someone was caught with a modafid radio or not, if anyone knows please let us know.
Hi from Turkey..I need some help please..I have a variable..I connected all the corners..and now it is 35-330 pf ..but I need less the 35..minimal capacitance must be 10 for example..what can I do for this ?
I strugle with knowing how you wire the bloody things. Still dont know. whats + and whats -. The second one you show is exactly the same as what I have here, I got it out of an old signal generator but I still have no idea what it's capacitance range is my cheap chinease capacitance tester wont recognise it. Great video you made here, not only do I now know what is + and - on my capacitor but I now also know exactly it's capacitance value 2X 500pf total of 1000pf. Any idea how to wire it for a mag loop?
Greetings to you dear friend, how can I make a very powerful external antenna .... I went in the past few days to the old used radio market and got one with a variable metal capacitor like the one you are explaining on now, in addition to the ferrite column and the wire around it and after removing it From the old radio, I did not know how to connect it to make an antenna for the radio, knowing that there are many and many videos on TH-cam explaining this, but I am confused about the correct way, please help
Hi Muhammad. I may be able to help a little; but you must first tell me, what radio signals do you want to receive? Is it AM or FM? Is it Medium Wave, or Short Wave? Also, please tell me where you live, and what radio stations you want to receive. I will help you if I can. You mentioned the ferrite rod (=column) and the coil round it - If you still have the wires (the coils) around it, that will be important. First, reply here, OK? Best wishes. Norman.
@@bixanorak th-cam.com/video/IWKo2iPEmlI/w-d-xo.html It is the video clip of the metal variable capacitor that I have with the ferrite column with the coil as it is when I removed it from the old radio. I also have a radio. I will record a clip of it shortly and send you the link. I live in the Arabian Gulf and I want to listen to the short, medium and very short waves, and there is no specific channel I want By listening to it, I would like to listen to meaningful audio programs such as antiquity
@@muhammadslwaey8829 Unfortunately, Muhammad, your TH-cam video is 'Private' - so only you can watch it. 😙 But I will wait to see what pther info. you send. One very effective (small and easy) antenna for long & medium wave, is the 'Frame Antenna' (Loop Antenna) - see examples on TH-cam by searching for "'Medium Wave Loop Antenna" and "Medium Wave Frame Antenna". Good luck! Norman.
Hi, I have a small question about the variable capacitor, if it is possible to clarify. I remember seeing in some publication, but I do not remember where, on the outermost rotor plates that have a mark, three cuts, I do not know if this is the correct term, and that they are used for reference to certain frequencies, but I also do not remember which frequencies. Could you tell me? Thanks..
Hi there, Valdir. The outermost rotor plates have those little cuts so you can *slightly* adjust the total capacitance. They are, naturally, on the outside vanes in case you want to slightly *decrease* the total capacitance, by carefully bending one or more of the slotted vanes *outwards*. To slightly *increase* the capacitance, you bent them in - but not to touch the next plate! This was especially useful if you had more than one 'gang' of plates. Some variable capacitors had two , three, sometimes even four separate sets of plates - like the 'two gang' capacitor at 3' 25" in the video. These were used to tune two (or more) circuits that had to be in synch. If the gangs did not have *almost exactly* the same capacitance, then the circuits would go out of synchronism, and the performance of the radio would not be optimum. Sometimes, each gang of a variable capacitor would have a small 'compression trimmer' attached to each gang, like the trimmer shown at 11' 38" in the video. These 'trimmers' enabled you to get the big capacitors the same value. Or at least, *very close*. 8^) Hope this is of help. Best wishes & good luck! Norman.
Glad you liked it - I'd forgotten about the 'minimalist' receiver at the end! It has been said that if you stick two different metals into a potato, that will detect AM radio.... must try it! Cheers, Norman.
THank you. How many turns did you use on the coil and what was the copper guage of the wire? What diameter? Thank you. And if you have a diagram of the amplifier part I would like to have it please.
Hi, and thanks for writing. Well, that coil was for the Long Wave (~150 KHz to ~300 KHz) so it was made on 2.5" (6.5cm) diameter plastic drainpipe, with about 150 turns of close-wound enamelled copper wire (called magnet wire in the U.S.) of 0.45mm diameter. That’s 26 S.W.G. (British Standard Wire Gauge), or 25 A.W.G. (American Wire Gauge). However, the gauge is not very important - but it MUST be enamelled (insulated). What is important, Long Wave broadcasting is, I believe, only used in Europe; so if you’re outside Europe, there almost certainly won’t be anything for you to receive! But there will be stuff on the Medium Wave (~525 KHz to ~1600 KHz.) To tune the Medium Waveband with a 500 pF variable capacitor like I used, make a coil on, say, 1.5" (~4cm) plastic pipe, of about 60 turns, and that should do. The amplifier I used was just an ordinary audio amplifier. You could put the signal into the sound card of a PC or laptop. Or a guitar amplifier if you have one. Cheap, small audio amplifier modules are readily available on ebay. If you’d like more details, go to my (very long!) series of 6 videos on making Crystal & valve radios. #1 is at th-cam.com/video/EJrG9pfvf4U/w-d-xo.html Hope this helps, & good luck with your project! Norman.
IMHO, the most likely source is radio hams, most of whom traditionally maintain 'junk boxes' of things that may come in handy one day for some project or other. Since air-spaced variable capacitors were always relatively expensive, few hams ever throw them away. Therefore, to find radio hams, Google to see if there is an amateur radio society anywhere near you. If there is, find out when & where they meet & just turn up and introduce yourself. Hams have always been very accessible and are keen to encourage interest in radio of any kind, and at whatever level. Newcomers are always welcomed. The phrase was always "The Ham Spirit" - and it is still very much alive! Good luck. Norman, G4LQF.
Yes; there are two main things: (a) what is the job the capacitor has to do - some jobs require a large capacitance, while others need very small capacitance; and (b) the voltage present across the capacitor. This may be a few microvolts, or it may be hundreds or even thousands of volts. The capacitor needs to be able to withstand high voltages without 'breaking down' under the 'pressure' of the voltage. Hope of help; cheers, Norman.
That is a good idea - thanks. The variometer (variable inductor) would act with the capacitance of the antenna & so give a tunable resonant frequency. This would of course *reject* incoming signals of around that frequency, and divert them to the detector; this would most likely have been a crystal detector - or perhaps even a valve. To sum up, as you have suggested, it is NOT necessary to have a variable capacitor in a simple radio receiver! Best regards, Norman.
![เปิดบ้าน โคตรสวย ป๋องกพล รู้จักตั้งนาน เพิ่งรู้ว่ารวย!!! l [Nickynachat]](http://i.ytimg.com/vi/tmgCF_2HfYI/mqdefault.jpg)
![เป็นไปได้ไหม - WanMai [Official MV]](http://i.ytimg.com/vi/_6lZ6b3_7Vo/mqdefault.jpg)
Thank you Norman. I realize this video is from the way back machine, but it answered a question for me about crystal radios. I built one in about 1959 or 60 when I was 10 or 11, now I'm reliving my childhood I guess, because I decided to build one and did a few days ago. Just checking up to see if I got it right, now I need to get some alligator clips for ground and antenna.
Excellent, Norman!! Thank you so much for sharing your knowledge and insight-and enthusiasm! Informative and well done.
Brilliant! I recently decided to build a SW radio from an old Archer kit schematic and bought a 365 pF varicap. Was surprised to see four terminals, not two as the smaller, plastic one in the original kit had. Attached a knob, hooked up capacitance meter probes to opposite-side terminals- no change whatsoever. Kept trying different terminals. Same damned thing. WTF?!?! Found your video via Google. I used to think that I knew something about electronics, but that's the side of me that reads Jim Williams but doesn't like dragging itself to the breadboard and doing anything *practical.* THANK YOU!!!
أنا ادرسها الآن في صفي الثاني عشر وإتيت لهذا الفيديو الآن لكي أرى عملها عمليًا ، شكرًا لمن أعَدَ هذا الفيديو 🧡
أشكركم على رسالتكم. إذا كان الفيديو مفيدًا لك ، فهذه مكافأتي العظيمة. دع كل الحظ الجيد يذهب معك في المستقبل.
@@bixanorak ❤️❤️❤️
الجهاز شنو اسمه
I enjoyed that so much thanks! I'm just getting back into amateur radio after a 30 year break and it was good to go back to basics and go through all the types of variable capacitor. You explained this simply and clearly..
Hey there! Yes - everybody seems to have these lay-offs, in order to attend to stuff like kids growing up, needing attention & guidance &c.!! But it's nice to come back to 'an old friend' hobby. Wishing you all the best with it. Take care, & best 73, Norman G4LQF, ex-WS0B.
I have been reviewing your crystal radio videos and bought a 365 pf variable cap and wound up a coil on two inch PVC with radio shack mag wire. Interesting so far I have two stations in the high end of the am like 1310 etc. Not sure what coil modification will make it tune further down the frequency range. Thanks Norman you're the man!
+area46241 Hi there - thanks for writing. just make the coil maybe twice as many turns - fasten the new end down temporarily with sellotape or insulating tape - that will get you down to a lower frequency. If it's too low, take off a few turns, until you get the widest coverage. It may not tune the whole range of the Medium Wave. However, if your 365 pF is a twin gang and you're only using one gang, put both gangs in parallel, which will give you 730 pF. You might try this before adding turns... You could also have a small fixed capacitor - say 220 pF - in parallel with your 365 pF. Tiny disc ceramic fixed capacitors are cheap & will work OK. Good luck!
He is really good... I found this really useful as well... Impressed by his teaching way!
I know all of this material and its good to have quick hands on access to demos, thanks!
Hi Jim. Thanks for writing - you're welcome & glad you found it OK. All the best to you & yours for Xmas 2021! Cheers, Norman.
Thank you again, lovely capacitor from the 30's. Thumbs up!
Once again you did an outstanding job FB. I had always wondered what was connected to ground. I'm going to check the crystal set I built about 5 years ago to see if I did it right. I was only getting one station.
Keep your videos coming I enjoy them all
I recently saw one of these in a FranLab video and hadn't seen them before. Very neat. Can't say I'm very familiar with air-gap capacitors. Makes sense that they're such low capacitance
thanks!....it helped me hetting how variable capacitors work basically
Philips commercial 2-way FM transceivers from the 1960s were full of those beehive trimmers. They could be converted to the amateur 6 metre band. I tried it but could never get the thing to transmit consistently , but it would receive.
Thank you so much for all rhe information, I learned a lot and your accent is beuatiful.
Thanks so much for another informative presentation Norman.
Now you put this video out We won't be able to get any more of those old Variable Capacitors for love nor money haha, Thanks for the video Norman.
Thank you. Now I know how to set up my Mag Loop.
Gracias por explicar esto. Gracias por tu conocimiento.
Old is gold
Thank you for the your videos.
Thank you for your courtesy in replying! If the video was helpful to you, then it has served a purpose which exceeded my humble effort in making the video! Wishing you the very best of good fortune in your future career. Norman.
Thank you sir i am a student and i d love to see how variable capacitor looks like 👍 great job
Thank you for writing - glad you found the vido of interest. Very best wishes for success in your studies! Norman.
Perhaps only for a certain band in a tuner or receiver in a single gang otherwise that double gang used for AM / FM tuner.
Yayy you explain things so well it's quite enjoyable (: ❤
Hey Denny - glad you liked it! Cheers, Norman.
I've seen that types in our TOSHIBA transistor radio 📻 late 70's model
and NATIONAL Accutrac X2 stereo component.
Back in the days of RADIO FREE EUROPE when the U.S. was transmitting radio into the Soviet blocked countries behind what at the time was called the iron curtain. To prevent the people that lived in the blocked countries from receiveing the U.S. broadcasts the cap had small bumps on two opposing plates that came in contact with one another shorting out the cap and preventing the osalator from osalating on that frequency and preventing the radio from receiveing the frequency that the U.S. transmitted on. Some of the people would file down the bumps so they no longer made contact so they could still receive the U.S. brodcasts. I don't I don't know if there was a penalty if someone was caught with a modafid radio or not, if anyone knows please let us know.
Awesome video
Hi from Turkey..I need some help please..I have a variable..I connected all the corners..and now it is 35-330 pf ..but I need less the 35..minimal capacitance must be 10 for example..what can I do for this ?
Hope you have a happy new 2021
Thank you very much! And also, I wish you all success in 2021 - best regards & Stay Safe. Norman.
if variable capacitor is used to build WM ferrite bar antenna, would it be better off with a large pf (1000pf) compare to a 365pf unit. thx
Thank you so much sir♥♥♥
What type of capacitor would I use if I wanted to hear all stations at once?
Just use a coil without the capacitor, all the strong AM stations will boom in all at once. It will be a mess to hear😄
All radio gang condenser values same or not sir
I strugle with knowing how you wire the bloody things. Still dont know. whats + and whats -.
The second one you show is exactly the same as what I have here, I got it out of an old signal generator but I still have no idea what it's capacitance range is my cheap chinease capacitance tester wont recognise it.
Great video you made here, not only do I now know what is + and - on my capacitor but I now also know exactly it's capacitance value 2X 500pf total of 1000pf.
Any idea how to wire it for a mag loop?
@ 07:00 Couldn't resist! Love a good pun :)
Greetings to you dear friend, how can I make a very powerful external antenna .... I went in the past few days to the old used radio market and got one with a variable metal capacitor like the one you are explaining on now, in addition to the ferrite column and the wire around it and after removing it From the old radio, I did not know how to connect it to make an antenna for the radio, knowing that there are many and many videos on TH-cam explaining this, but I am confused about the correct way, please help
Hi Muhammad. I may be able to help a little; but you must first tell me, what radio signals do you want to receive? Is it AM or FM? Is it Medium Wave, or Short Wave? Also, please tell me where you live, and what radio stations you want to receive. I will help you if I can. You mentioned the ferrite rod (=column) and the coil round it - If you still have the wires (the coils) around it, that will be important. First, reply here, OK? Best wishes. Norman.
@@bixanorak th-cam.com/video/IWKo2iPEmlI/w-d-xo.html It is the video clip of the metal variable capacitor that I have with the ferrite column with the coil as it is when I removed it from the old radio. I also have a radio. I will record a clip of it shortly and send you the link. I live in the Arabian Gulf and I want to listen to the short, medium and very short waves, and there is no specific channel I want By listening to it, I would like to listen to meaningful audio programs such as antiquity
@@muhammadslwaey8829 Unfortunately, Muhammad, your TH-cam video is 'Private' - so only you can watch it. 😙 But I will wait to see what pther info. you send. One very effective (small and easy) antenna for long & medium wave, is the 'Frame Antenna' (Loop Antenna) - see examples on TH-cam by searching for "'Medium Wave Loop Antenna" and "Medium Wave Frame Antenna". Good luck! Norman.
Good luck sir 🎉
You are very kind to write! Thank you, & all future success to you and your family. Sincere regards, Norman.
Thank you.
Hi, I have a small question about the variable capacitor, if it is possible to clarify. I remember seeing in some publication, but I do not remember where, on the outermost rotor plates that have a mark, three cuts, I do not know if this is the correct term, and that they are used for reference to certain frequencies, but I also do not remember which frequencies. Could you tell me? Thanks..
Hi there, Valdir. The outermost rotor plates have those little cuts so you can *slightly* adjust the total capacitance. They are, naturally, on the outside vanes in case you want to slightly *decrease* the total capacitance, by carefully bending one or more of the slotted vanes *outwards*. To slightly *increase* the capacitance, you bent them in - but not to touch the next plate! This was especially useful if you had more than one 'gang' of plates. Some variable capacitors had two , three, sometimes even four separate sets of plates - like the 'two gang' capacitor at 3' 25" in the video. These were used to tune two (or more) circuits that had to be in synch. If the gangs did not have *almost exactly* the same capacitance, then the circuits would go out of synchronism, and the performance of the radio would not be optimum. Sometimes, each gang of a variable capacitor would have a small 'compression trimmer' attached to each gang, like the trimmer shown at 11' 38" in the video. These 'trimmers' enabled you to get the big capacitors the same value. Or at least, *very close*. 8^) Hope this is of help. Best wishes & good luck! Norman.
Thanks for the info, Norman. Best wishes.
Wonderful lesson. Thank you. I enjoyed the end edit part also.
Glad you liked it - I'd forgotten about the 'minimalist' receiver at the end! It has been said that if you stick two different metals into a potato, that will detect AM radio.... must try it! Cheers, Norman.
THank you. How many turns did you use on the coil and what was the copper guage of the wire? What diameter? Thank you. And if you have a diagram of the amplifier part I would like to have it please.
Hi, and thanks for writing.
Well, that coil was for the Long Wave (~150 KHz to ~300 KHz) so it was made on 2.5" (6.5cm) diameter plastic drainpipe, with about 150 turns of close-wound enamelled copper wire (called magnet wire in the U.S.) of 0.45mm diameter. That’s 26 S.W.G. (British Standard Wire Gauge), or 25 A.W.G. (American Wire Gauge). However, the gauge is not very important - but it MUST be enamelled (insulated).
What is important, Long Wave broadcasting is, I believe, only used in Europe; so if you’re outside Europe, there almost certainly won’t be anything for you to receive! But there will be stuff on the Medium Wave (~525 KHz to ~1600 KHz.)
To tune the Medium Waveband with a 500 pF variable capacitor like I used, make a coil on, say, 1.5" (~4cm) plastic pipe, of about 60 turns, and that should do.
The amplifier I used was just an ordinary audio amplifier. You could put the signal into the sound card of a PC or laptop. Or a guitar amplifier if you have one. Cheap, small audio amplifier modules are readily available on ebay.
If you’d like more details, go to my (very long!) series of 6 videos on making Crystal & valve radios. #1 is at th-cam.com/video/EJrG9pfvf4U/w-d-xo.html Hope this helps, & good luck with your project! Norman.
Cool video...and great shirt!
Is there a good source for the VC Caps-- other then Pebble?
IMHO, the most likely source is radio hams, most of whom traditionally maintain 'junk boxes' of things that may come in handy one day for some project or other. Since air-spaced variable capacitors were always relatively expensive, few hams ever throw them away. Therefore, to find radio hams, Google to see if there is an amateur radio society anywhere near you. If there is, find out when & where they meet & just turn up and introduce yourself. Hams have always been very accessible and are keen to encourage interest in radio of any kind, and at whatever level. Newcomers are always welcomed. The phrase was always "The Ham Spirit" - and it is still very much alive! Good luck. Norman, G4LQF.
I live in a CRAPPY little town with NO resources to parts of any kind. Is IHMO a company?
Thanks Norman
Thanks Norman, what do you think of the work of the late Dr. Thomas Henry Moray.
Hi from 2022😂 thanks for the video!
Thanks for the video. Liked.
Does it matter what capacitor to use
Yes; there are two main things: (a) what is the job the capacitor has to do - some jobs require a large capacitance, while others need very small capacitance; and (b) the voltage present across the capacitor. This may be a few microvolts, or it may be hundreds or even thousands of volts. The capacitor needs to be able to withstand high voltages without 'breaking down' under the 'pressure' of the voltage. Hope of help; cheers, Norman.
Why not use old style variometer coils.... ? Its like more1910... 1920s..
That is a good idea - thanks. The variometer (variable inductor) would act with the capacitance of the antenna & so give a tunable resonant frequency. This would of course *reject* incoming signals of around that frequency, and divert them to the detector; this would most likely have been a crystal detector - or perhaps even a valve. To sum up, as you have suggested, it is NOT necessary to have a variable capacitor in a simple radio receiver! Best regards, Norman.
Thank u 💓
Uuuum, what are vanes in a variable capacitor? Don't you mean PLATES?
Thanks boss
Radial capaciters or axail.. there is a difference..
thanku☺
Glad it was of help! Cheers, Norman.
Nicely this remaind me when i 12 years old but i dont understand what is it
thanks
طالبه سادس 2023
If anyone could test this app i'd be grateful! Track down androidcircuitsolver on google
Who else studying that for school report
Thanks for writing, and wishing you all success in your career. Best regards, Norman.
اي اخيك طالب سادس
طلعت مو بس انه الي اذا ما اشوف الشي شلون يشتغل ما افتهمه ولا احفظه 😂😂💔