Скачать или смотреть A new and original "Ring Modulator" design

This is what I believe to be an original concept for a ring modulator, which does not use either transformers or an analog multiplier IC.

It's a PWM based device, using all readily available and reasonably low cost parts.

The full downloadable schematics are available on my web site here, along with more details:
http://robert-jenkins.co.uk/site/inde...

The preset and flying resistor at the lower left are a test for a fine carrier null adjustment. It did not seem to do anything in the first trial when the levels were too high, but does work and was set correctly for the second test, significantly reducing audio passthrough with no modulating carrier.

The preset is across 0V & 5V with a 1M resistor connected from the wiper directly to the channel input pin on the PAM8403 IC. It would need that circuit duplicating for the other carrier input.

It's not shown in the preliminary schematics, I will add it in an update.

00:00:00 Intro - a few brief audio samples
00:00:10 Background & the prototype
00:00:44 The PWM generator (carrier input)
00:01:14 74HC86 XOR gate to produce true and inverse PWM
00:01:36 Analog switches; selects true & inverse PWM, inputs true and inverse audio.
00:01:44 Audio inputs, buffer amp and inverting amp
00:01:58 Signal paths
00:03:04 Low pass filters for PWM carrier removal
00:03:18 Compromises in the prototype
00:04:04 Test setup: Audio source, mic preamp & SM58
00:04:32 Carrier source, from function generator
00:05:07 Output isolation & connection to Focusrite Scarlett
00:05:20 Recording software - Audacity
00:05:33 Why it's built as Stereo or two channel
00:05:59 Schematics on my web site
00:06:53 Please like and subscribe!
00:07:07 Test audio (after adding gain preset etc).