Timeline for How to fix when the amplitude modulated signal reaches the peak, the bottom follows too?
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| when toggle format | what | by | license | comment | |
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| Nov 15, 2021 at 6:36 | history | edited | Eddy Miner | CC BY-SA 4.0 |
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| Nov 15, 2021 at 5:00 | comment | added | Eddy Miner | I believe its the third link. I read through the website before but I realized that their Ec is lower than Em, which is weird in my thought. What I understand is Em should be lower than Ec in order to produce a good modulation index. So I not using their idea at first, although it success | |
| Nov 15, 2021 at 4:51 | comment | added | jay | one here, and another, and the other. All original, Dang!, my wrist hurt. I should not give too much credit to the originals. @EddyMiner , I will give you my original idea, once you tell me which one was "the" original. | |
| Nov 15, 2021 at 4:42 | comment | added | Eddy Miner | @jonk My mistake for it. For the time now, I prefer to design a common emitter amplifier with variable gain to create amplitude modulation. I try to design by just adding a message at the biasing circuit. Please correct me if there's any mistake | |
| Nov 15, 2021 at 4:29 | comment | added | jonk | @EddyMiner Many ideas. But I don't know your constraints. If it is nothing more than "you can explain it" then you will have to spend a lot of time telling me about what you can explain and what you cannot explain. A carrier, fed to a variable voltage gain amplifier, gets you there if you can take the absolute value of your input AC. Forget the absolute value part of this. How would you construct a VGA from a BJT stage? | |
| Nov 15, 2021 at 3:57 | answer | added | Math Keeps Me Busy | timeline score: 1 | |
| Nov 15, 2021 at 3:48 | answer | added | glen_geek | timeline score: 1 | |
| Nov 15, 2021 at 3:26 | comment | added | Eddy Miner | @jay Any better options for this? | |
| Nov 15, 2021 at 3:26 | comment | added | Eddy Miner | @jonk I have to make it a simple circuit with transistor to amplify so that I can explain to other people. Do you have any idea on it? | |
| Nov 15, 2021 at 3:25 | comment | added | Eddy Miner | @KevinWhite I have tried to high pass it by configuring the capacitor and resistor values at the right side. But the result is the same with lower amplitude. The capacitor value is 160nF and resistor is 1kohm. | |
| Nov 15, 2021 at 2:34 | answer | added | Audioguru | timeline score: 0 | |
| Nov 15, 2021 at 2:26 | comment | added | jonk | Eddy, @KevinWhite has nailed the approach. There are two methods for DSB: either a square law modulator or else a switching AM modulator. Personally, since I have a few thousand of them, I'd just use an MC1496. It's faster than you need yet it works fine with low frequencies. Here's an example case simulation, though I used smaller caps (higher modulation frequencies here) and used 1 kHz to modulate 10 MHz. Still, it gets one point across: what it should look like. | |
| Nov 15, 2021 at 2:25 | comment | added | jay | Incorrect configuration. That is 'no' AM signal. | |
| Nov 15, 2021 at 2:04 | comment | added | Kevin White | There is probably a small amount of modulation in there but it is dwarfed by the feed through of the 10 Hz modulating signal. To see the modulation you need to high-pass the signal to remove the 10Hz signal on the output. Lookup "balanced modulator". | |
| Nov 15, 2021 at 1:59 | comment | added | Dave Tweed | Clamp/clip the negative swings at 0V, then run it through a bandpass filter. | |
| Nov 15, 2021 at 1:41 | comment | added | Math Keeps Me Busy | @jsotola the OP's circuit is found on the interwebs, listed as an amplitude modulator, such as electronique1.blogspot.com/2011/02/transistor-am-modulator.html | |
| Nov 15, 2021 at 1:26 | comment | added | jsotola | the output signal is not amplitude modulated per se ... it is shifted with respect to local ground reference ... if you fed that signal to an RF transmitter, then the modulation would be invisible at the receiving end | |
| Nov 15, 2021 at 1:01 | history | edited | ocrdu | CC BY-SA 4.0 |
added 10 characters in body
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| S Nov 15, 2021 at 0:55 | review | First questions | |||
| Nov 15, 2021 at 1:01 | |||||
| S Nov 15, 2021 at 0:55 | history | asked | Eddy Miner | CC BY-SA 4.0 |
