Has anyone build a class D amplifier using relays only? The operation of a class D amplifier involves the varying of the pulse with based on the input signal, presumably the signal could be used to switch a much large current than the input signal, resulting in amplification.
I am no quite sure how this would work, and I was unable to find any references to using relays in this way except for the use of 'reed relays' in telephone switching systems.
What is a Reed Relay? from Pickering Electronics - YouTube
I am no quite sure how this would work, and I was unable to find any references to using relays in this way except for the use of 'reed relays' in telephone switching systems.
What is a Reed Relay? from Pickering Electronics - YouTube
I think Digikey has several types of those relays in stock.
And computers are starting to use them too.
Relay Computer - WikiChip
And computers are starting to use them too.
Relay Computer - WikiChip
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What you describe exists, and has been used in the early part of the 20th century: it is a carbon microphone telephone repeater
I thought the frequency had to be just more than double the highest frequency reproduced, ie 50 kHz.
I might work as a curiosity or, simplicity and the ability to handle high currents might be an advantage.
A magnetic contactless relay might help increase reliability.
The Hall Effect sensor seems a little slow on the uptake:
Basic Hall Effect Sensors 1 - YouTube
A car with an old-style generator, the voltage regulator is a relay using "Class D" concept to modulate the field coil and adjust the generator output. Response speed is fast enough for a lead-acid battery but far below the bottom of the audio band.
IMHO, a carbon mike is "linear". Each contact has a small range of semi-proportional resistance; over thousands of contacts we get a useful linear range. (Notwithstanding 20% THD.)
IMHO, a carbon mike is "linear". Each contact has a small range of semi-proportional resistance; over thousands of contacts we get a useful linear range. (Notwithstanding 20% THD.)
Why not go straight to an 8 or 16 bit DAC using relays? Just switch on/off 16 "weighted" resistors into a constant resistive load, perhaps that could even be a speaker!
The highest frequency you could make would depend on the sample rate, which would depend on the relay switching speed. A quick Google says 1 kHz. That should cover sub-woofer territory, say, 100 Hz on down with better than 10 samples / cycle.
Unfortunately, you'd need an ADC to get the bits from an analog audio signal to drive the relays with. Does it still count as "no transistors or tubes"? Or can you use anything you want, as long as its not doing the amplification of voltage or current?
The highest frequency you could make would depend on the sample rate, which would depend on the relay switching speed. A quick Google says 1 kHz. That should cover sub-woofer territory, say, 100 Hz on down with better than 10 samples / cycle.
Unfortunately, you'd need an ADC to get the bits from an analog audio signal to drive the relays with. Does it still count as "no transistors or tubes"? Or can you use anything you want, as long as its not doing the amplification of voltage or current?
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