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I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial communication at 115200Hz). The receiver consists of a photodiode, amplifiers, filters, and it requires an envelope detector or a circuit that outputs high when theres a AC signal present.

I've tried using a

  1. Envelope detectorA full and half bridge rectifier(https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detectorwith capacitor):

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. Envelope detector (https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detector):

It produces a lot of voltage spikes from capacitor discharging and does not really produce any recognizable demodulated wave

  1. A full and half bridge rectifier(with capacitor)

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. A diode and transistor

Transistor has quite a high breakdown voltage at 0.7V and the capacitor's response time is way too fast

  1. A diode and capacitor

This circuit works for low signal frequencies but fails at higher signal frequencies

I'm also considering using a slow op-amp with response time faster than signal but slower than carrier wave, would it be reasonable? If so how should I build the circuit. Will there be any better options?

I have access to basic resistors, capacitors, some transistors and diodes, other components would have to be sourced.

Voltage graph after amplification and filtering: after amp and filtering

Voltage graph with diode pointing away from ground: with diode

Amplifier with filter: amp with filter

Circuits tried: Circuits tried

I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial communication at 115200Hz). The receiver consists of a photodiode, amplifiers, filters, and it requires an envelope detector or a circuit that outputs high when theres a AC signal present.

I've tried using a

  1. Envelope detector(https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detector):

It produces a lot of voltage spikes from capacitor discharging and does not really produce any recognizable demodulated wave

  1. A full and half bridge rectifier(with capacitor)

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. A diode and transistor

Transistor has quite a high breakdown voltage at 0.7V and the capacitor's response time is way too fast

  1. A diode and capacitor

This circuit works for low signal frequencies but fails at higher signal frequencies

I'm also considering using a slow op-amp with response time faster than signal but slower than carrier wave, would it be reasonable? If so how should I build the circuit. Will there be any better options?

I have access to basic resistors, capacitors, some transistors and diodes, other components would have to be sourced.

Voltage graph after amplification and filtering: after amp and filtering

Voltage graph with diode pointing away from ground: with diode

Amplifier with filter: amp with filter

I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial communication at 115200Hz). The receiver consists of a photodiode, amplifiers, filters, and it requires an envelope detector or a circuit that outputs high when theres a AC signal present.

I've tried using a

  1. A full and half bridge rectifier(with capacitor)

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. Envelope detector (https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detector):

It produces a lot of voltage spikes from capacitor discharging and does not really produce any recognizable demodulated wave

  1. A diode and transistor

Transistor has quite a high breakdown voltage at 0.7V and the capacitor's response time is way too fast

  1. A diode and capacitor

This circuit works for low signal frequencies but fails at higher signal frequencies

I'm also considering using a slow op-amp with response time faster than signal but slower than carrier wave, would it be reasonable? If so how should I build the circuit. Will there be any better options?

I have access to basic resistors, capacitors, some transistors and diodes, other components would have to be sourced.

Voltage graph after amplification and filtering: after amp and filtering

Voltage graph with diode pointing away from ground: with diode

Amplifier with filter: amp with filter

Circuits tried: Circuits tried

2 added 97 characters in body; added 1 character in body
source | link

I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial communication at 115200Hz). The receiver consists of a photodiode, amplifiers, filters, and it requires an envelope detector or a circuit that outputs high when theres a AC signal present.

I've tried using a

  1. Envelope detector(https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detector):

It produces a lot of voltage spikes from capacitor discharging and does not really produce any recognizable demodulated wave

  1. A full and half bridge rectifier(with capacitor)

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. A diode and transistor

Transistor has quite a high breakdown voltage at 0.7V and the capacitor's response time is way too fast

  1. A diode and capacitor

This circuit works for low signal frequencies but fails at higher signal frequencies

I'm also considering using a slow op-amp with response time faster than signal but slower than carrier wave, would it be reasonable? If so how should I build the circuit. Will there be any better options?

I have access to basic resistors, capacitors, some transistors and diodes, other components would have to be sourced.

Voltage graph after amplification and filtering: after amp and filtering

Voltage graph with diode pointing away from ground: with diode

Amplifier with filter: amp with filter

I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial communication at 115200Hz). The receiver consists of a photodiode, amplifiers, filters, and it requires an envelope detector or a circuit that outputs high when theres a AC signal present.

I've tried using a

  1. Envelope detector(https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detector):

It produces a lot of voltage spikes from capacitor discharging and does not really produce any recognizable demodulated wave

  1. A full and half bridge rectifier(with capacitor)

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. A diode and transistor

Transistor has quite a high breakdown voltage at 0.7V and the capacitor's response time is way too fast

  1. A diode and capacitor

This circuit works for low signal frequencies but fails at higher signal frequencies

I'm also considering using a slow op-amp with response time faster than signal but slower than carrier wave, would it be reasonable? If so how should I build the circuit. Will there be any better options?

I have access to basic resistors, capacitors, some transistors and diodes, other components would have to be sourced.

Voltage graph after amplification and filtering: after amp and filtering

Voltage graph with diode pointing away from ground: with diode

I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial communication at 115200Hz). The receiver consists of a photodiode, amplifiers, filters, and it requires an envelope detector or a circuit that outputs high when theres a AC signal present.

I've tried using a

  1. Envelope detector(https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detector):

It produces a lot of voltage spikes from capacitor discharging and does not really produce any recognizable demodulated wave

  1. A full and half bridge rectifier(with capacitor)

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. A diode and transistor

Transistor has quite a high breakdown voltage at 0.7V and the capacitor's response time is way too fast

  1. A diode and capacitor

This circuit works for low signal frequencies but fails at higher signal frequencies

I'm also considering using a slow op-amp with response time faster than signal but slower than carrier wave, would it be reasonable? If so how should I build the circuit. Will there be any better options?

I have access to basic resistors, capacitors, some transistors and diodes, other components would have to be sourced.

Voltage graph after amplification and filtering: after amp and filtering

Voltage graph with diode pointing away from ground: with diode

Amplifier with filter: amp with filter

1
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High frequency AM demodulation

I'm building an light communication device(pretty much lifi) using AM and am mostly done with every part except for demodulating the signal. The signal looks like with a 1.8432MHz carrier wave(serial communication at 115200Hz). The receiver consists of a photodiode, amplifiers, filters, and it requires an envelope detector or a circuit that outputs high when theres a AC signal present.

I've tried using a

  1. Envelope detector(https://en.wikipedia.org/wiki/Envelope_detector#/media/File:Simple_envelope_detector.svg, basically peak detector):

It produces a lot of voltage spikes from capacitor discharging and does not really produce any recognizable demodulated wave

  1. A full and half bridge rectifier(with capacitor)

A lot of signal is suppressed with this can capacitor just shunts everything to ground.

  1. A diode and transistor

Transistor has quite a high breakdown voltage at 0.7V and the capacitor's response time is way too fast

  1. A diode and capacitor

This circuit works for low signal frequencies but fails at higher signal frequencies

I'm also considering using a slow op-amp with response time faster than signal but slower than carrier wave, would it be reasonable? If so how should I build the circuit. Will there be any better options?

I have access to basic resistors, capacitors, some transistors and diodes, other components would have to be sourced.

Voltage graph after amplification and filtering: after amp and filtering

Voltage graph with diode pointing away from ground: with diode