This receiver is a simplified version of my quadrature sampling receiver. It is simplified because it does not require the phasing filter section and also does not divide the LO by 4. This simplifies the local oscillator requirements significantly. The receiver uses a 2 pole low pass filter for selectivity and a TDA7052 audio amplifier. The CS2000 is a SPI controlled clock generator and is used for frequency generation and tuning, but any VFO, VXO or any other stable frequency source will work. In this case, one of the extra inverter stages could be used as a linear amplifier to boost up the oscillator output if required(need a good squarewave). If this is done, the micro-controller can be eliminated. The input RF amplifier can also be eliminated if you are using an approximately 50 ohm resonant antenna. In this case the antenna would connect through C13 to pin 9 of IC5. If you do this – pin 9 must also be biased to 1/2 supply. This can be done with a couple of 4.7k resistors connected in series from V+ to Gnd. The center junction point will go to pin 9.
This receiver can receive AM but must be at zero beat(exactly tuned). The CS2000 has a resolution of 1Hz or so and is very stable – so the receiver work pretty well for AM. Unlike the phasing receiver this circuit cannot eliminate one of the side bands, but to be honest its not worth effort unless you want contest grade ham receiver performance.
In the video you can see I break out the power switch, audio gain, tuning encoder and display to a daughter board.
I designed the display to have very low spurious noise. The info on this is here:
More info about how this circuit works can be found in this post, which is the quadrature version of this receiver.
zip file of code: Filedropper is full of dumb ads but look for the “Download This File” button in middle of screen