Hi Matthew,what is your antenna connect at green alligator clip? In other case for RF input signal at mixer have you LC tank circuit to get the frequency for 1,2 Mhz? Dinos
Hi Matthew, Great video! I'm going to build this to use for a BFO circuit on a metal detector. What is the value of the capacitor at the LO input? I didn't see that in the video. Regards, Robert
Thanks for that. I used a 220 pf and built the circuit. It works (kind of). I have 2 (unstable) oscillators 1 at 1505 kc and the other at 1465 kc (checked on SW radio) and my DVM shows output of mixer wobbling around 45 to 50 kc for a while and then going to 0. According to the DVM the duty cycle is 5 to 7 % so very little of the output wave signal is above 0. It's a work in progress. For a metal detector I will need to adjust the oscillators to to adjust f1- f2 to get in the audio range and then run a speaker off of it. Maybe I'll put a low pass filter on the output. It's all good fun. Need to buy a "scope" which I have no idea what to buy. Thanks for your kind help!@@elpechos
@@robertschoenberg3972. Yeah, without a scope, it will be very difficult to work out what's going on. The output from this kind of mixer is generally very weak. You'll most likely need to filter out the undesired frequencies and amplify the desired ones, a few times. You may prefer to use a more modern approach. en.wikipedia.org/wiki/NE612 for simplicity
Hello Matthew, I checked on the Ne612 IC that you advised me of. In the end, this may be the final solution - thanks for that! Right now I am enjoying playing with discrete components and dealing with the ???, and confusion. I built a single oscillator metal detector and used it (with an AM radio) to find a buried irrigation valve. I am a retired mechanical engineer and life long electronic enthusiast and this is my hobby and interest. Need to buy a "scope", need to know what I need to know to buy a 'scope" - you know? Ha, ha. Thanks again and Cheers!@@elpechos
I've been working with 2N3904 transistors and I haven't been having success at frequencies above 1000 kHz. Maybe I can get some transistors like you are using and try them.
Thanks for the video. How will this receiver type handle a signal at the level of MHz? For example, let's assume that a 100Mhz signal is coming from the antenna in the FM band. How will the stage amplifier after the antenna amplify this high frequency? There isn't even a transistor to handle a 100Mhz signal.
There certainly is a lot of transitors that will handle 100Mhz. The ss9018 is a pretty old transitor with a transition frequency of 1.1Ghz. So it will handle 100Mhz no problem
Thanks for the video. So if I take a common emitter amplifier and inject a local oscillator frequency through the decoupling cap on the emitter resistor I get an RF mixer?
@@jemussi7842 You'd be better off buying a NE612 /SA602 though. It costs virtually the same as a single transistor and works a lot better. The one transistor mixer is more of historical interest. It does work well enough to make a simple superheterodyne AM radio though.
The reason it works is pretty mathsy and not intuitive. Plenty of places you can look up a derivation. The scope will just look like mess because it'll be 3 different frequencies all summed together. It'd be best viewed on a spectrum analyzer if anything
Thanks for the video : now i wonder why we use diodes and baluns when can just use active mixers (with tuned circuit) Please are your resistor values correct? doing the math then collector voltage is negative (bjt in saturation)... Please check it (what's my mistake? Thanks)
@Zeus . >i wonder why we use diodes and baluns when can just use active mixers Passive (eg, diode) mixers are simpler and have wider bandwidth than active mixers. They also tend to introduce less noise.
Steve again. Never mind. I think I know how you did it. You just made the 1200khz transmitting signal by creating a long antenna. Because all other signals are rejected except 2500khz. Right? Thanks in advance!
@@stevekim6923 Hi : like you said, with a long wire as antenna : I think : The radio station is broadcasting at 1.2khz but his radio can not pick it up because it is tuned at 2.5khz....With the mixer, the 1.2khz signal with audio from station is mixed with LO so that shifts the radio station signal to 2.5khz
@@Zeus-ub2zp That's exactly right. The RF input is coupled to the mixer via a long wire antenna. A short piece of wire is draped from the output over the radio to hear the result.
@@elpechos so basically you made a wire antenna and shifted all the RF frequencies 1.3 Mhz so 1.2Mhz became 2.5Mhz. But also many others moved by 1.3Mhz.
I Am HAPPY to financially support your work in exchange for you helping me with a RF mixer design. How do I contact you or get my contact information to you?
For total Noobs; An antenna converts invisable Electromagnetic radiation into pure electrical signal but you can also connect an electrical signal to the antenna and it will just go ahead and like it and say; "Thx for saving me the work" except not and electricity is always trying to play the magnet game at the same time. It's physics. Somebody way up high said that it was going to be that way. It lets us do cool stuff.
Simple and excellent demostration !!
Excellent! I tried this one back in 2012 in a discreet fm radio and worked fine.
Thank you for taking the time to do this video!!
I learned a lot ...Exactly what I needed....Excellent practical and simple...Thanks Matthew!
thank you because it's simple and with Genral transistor
Brilliance made simple 🎉 Thankyou
thank u for video pls share schematic of final assembly ,i am unable to understand .i understood as 1300khz to LO input .output to antenna and RF ????
Thanks for the practical demo.
where the collector output is connected and from were the green wire is coming
This mixer can use to receive airband signals in a AM radio? Please replay
Yes, and if you use it like that, you will also make an AM transmitter at the same time. Your neighbors will not like you for that.
It is a very interesting video about one transistor to get a mixer of signal. Thanks for sharing it, greetings from Mexico.
Hi Matthew,what is your antenna connect at green alligator clip?
In other case for RF input signal at mixer have you LC tank circuit to get the frequency for 1,2 Mhz?
Dinos
Thanks for this, I learned a lot.
Why it's now working in Pc simulation?
Loads of circuits that work fine in actual don't work in simulation, sir. I learned that hard way
Hi Matthew, Great video! I'm going to build this to use for a BFO circuit on a metal detector. What is the value of the capacitor at the LO input? I didn't see that in the video. Regards, Robert
I believed I used 10nF. It's not too critical
Thanks for that. I used a 220 pf and built the circuit. It works (kind of). I have 2 (unstable) oscillators 1 at 1505 kc and the other at 1465 kc (checked on SW radio) and my DVM shows output of mixer wobbling around 45 to 50 kc for a while and then going to 0. According to the DVM the duty cycle is 5 to 7 % so very little of the output wave signal is above 0. It's a work in progress. For a metal detector I will need to adjust the oscillators to to adjust f1- f2 to get in the audio range and then run a speaker off of it. Maybe I'll put a low pass filter on the output. It's all good fun. Need to buy a "scope" which I have no idea what to buy. Thanks for your kind help!@@elpechos
@@robertschoenberg3972. Yeah, without a scope, it will be very difficult to work out what's going on.
The output from this kind of mixer is generally very weak. You'll most likely need to filter out the undesired frequencies and amplify the desired ones, a few times.
You may prefer to use a more modern approach. en.wikipedia.org/wiki/NE612 for simplicity
Hello Matthew, I checked on the Ne612 IC that you advised me of. In the end, this may be the final solution - thanks for that! Right now I am enjoying playing with discrete components and dealing with the ???, and confusion. I built a single oscillator metal detector and used it (with an AM radio) to find a buried irrigation valve. I am a retired mechanical engineer and life long electronic enthusiast and this is my hobby and interest. Need to buy a "scope", need to know what I need to know to buy a 'scope" - you know? Ha, ha. Thanks again and Cheers!@@elpechos
Thanks. May I contact you I have some questions about the FM receiver circuit
I've been working with 2N3904 transistors and I haven't been having success at frequencies above 1000 kHz. Maybe I can get some transistors like you are using and try them.
Probably the High Frequency gain dramatic reduce after passing the midband
Thanks for the video. How will this receiver type handle a signal at the level of MHz? For example, let's assume that a 100Mhz signal is coming from the antenna in the FM band. How will the stage amplifier after the antenna amplify this high frequency? There isn't even a transistor to handle a 100Mhz signal.
There certainly is a lot of transitors that will handle 100Mhz. The ss9018 is a pretty old transitor with a transition frequency of 1.1Ghz. So it will handle 100Mhz no problem
Most will handle up to HF (High band frequency before the gain starts to decrease linear on dB).
Great video
Thank you for Sharing.
Would this work at 24MHz with a 2n2222a transistor
You need to find the datasheet and the max. freq.
Thanks for the video. So if I take a common emitter amplifier and inject a local oscillator frequency through the decoupling cap on the emitter resistor I get an RF mixer?
You sure do
@@elpechos Wow thanks! Must have learnt this once and forgot.
@@jemussi7842 You'd be better off buying a NE612
/SA602 though. It costs virtually the same as a single transistor and works a lot better. The one transistor mixer is more of historical interest. It does work well enough to make a simple superheterodyne AM radio though.
@@elpechos Many Thanks for this, I will look into that for sure.
Only if the levels are correct. If they are too small, then you are simply getting a linear adder circuit.
Nicely done !
Thank you Matthew!
that was a cool demo of the transistor type mixer / little, but effective for doing what it's you said it would do.
For some reason I'm having a difficult time wrapping my head around this concept, maybe if I saw the mixed signal on a scope.
The reason it works is pretty mathsy and not intuitive. Plenty of places you can look up a derivation.
The scope will just look like mess because it'll be 3 different frequencies all summed together.
It'd be best viewed on a spectrum analyzer if anything
@@elpechos Like modulated RF signal?
Thank You ! very easy to understand.
Cool. Thank you.
Thanks for the video : now i wonder why we use diodes and baluns when can just use active mixers (with tuned circuit)
Please are your resistor values correct? doing the math then collector voltage is negative (bjt in saturation)...
Please check it (what's my mistake? Thanks)
Here's the DC operating points for this amplifier
imgur.com/a/vevz7CR
You can always check your math with a free circuit simulator such as LTSpice
@Zeus .
>i wonder why we use diodes and baluns when can just use active mixers
Passive (eg, diode) mixers are simpler and have wider bandwidth than active mixers. They also tend to introduce less noise.
Exelente. Con esto puedo llegar hasta 50 mhz ?
Thanks
This is a fantastic video! One question I have is that how did you hook up the 1200khz transmitting signal to the input?
Thanks!
Steve again.
Never mind. I think I know how you did it. You just made the 1200khz transmitting signal by creating a long antenna. Because all other signals are rejected except 2500khz. Right?
Thanks in advance!
@@stevekim6923 Hi : like you said, with a long wire as antenna : I think : The radio station is broadcasting at 1.2khz but his radio can not pick it up because it is tuned at 2.5khz....With the mixer, the 1.2khz signal with audio from station is mixed with LO so that shifts the radio station signal to 2.5khz
@@Zeus-ub2zp That's exactly right. The RF input is coupled to the mixer via a long wire antenna. A short piece of wire is draped from the output over the radio to hear the result.
@@elpechos so basically you made a wire antenna and shifted all the RF frequencies 1.3 Mhz so 1.2Mhz became 2.5Mhz. But also many others moved by 1.3Mhz.
@@WoWPro71 yup
Amazing
Excellent!
Thanks!
Super
I Am HAPPY to financially support your work in exchange for you helping me with a RF mixer design. How do I contact you or get my contact information to you?
Why don't you just buy a ready to go radio? :-)
For total Noobs; An antenna converts invisable Electromagnetic radiation into pure electrical signal but you can also connect an electrical signal to the antenna and it will just go ahead and like it and say; "Thx for saving me the work" except not and electricity is always trying to play the magnet game at the same time. It's physics. Somebody way up high said that it was going to be that way. It lets us do cool stuff.
Yes, you are a total noob. :-)
Squilific ? No, extra scranologifraine Tattollogical !!!