SSR flickering output - i am using rectified audio output from stereo amp (half wave)

Thread Starter

edgar peace

Joined Nov 28, 2018
16
I'm doing a sound controlled christmas lighting. i bought an SSR with 3-32 vdc input and 24-380 VAC output. I inserted a 1n4001 diode to create a pulsating dc input. my problem is my AC output is flickering which means my input always falls below 3 vdc. Can i insert an RC circuit to smoothen my pulsating input? what value of resistor would i use so as not to attenuate my input voltage so much. i don't want my music volume to be very loud of course.
 

MaxHeadRoom

Joined Jul 18, 2013
19,145
The SSR output is going to switched on/off repeatedly, is this what you are hoping for?
The typical SSR units operate in the burst firing/zero cross switching method, not phase angle control.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
19,145
If the effect you are looking for is 'Dancing Lights' the SSR is not a good choice.
If you just need full on at loud passages, you need a storage device, large capacitor etc, or something like Bertus posted.
Max.
 

Tonyr1084

Joined Sep 24, 2015
3,625
I'm going to take a stab at a guess as to what your goal is: I'm thinking you want the lights to react to the amplitude of the audio wave form. At least that's what I'm thinking. If you want to light the light, use an RC circuit to prevent flicker then it pretty much sounds like you just want the light to come on when the music is playing.

One option is that you could go full wave rectification on your audio, then you'd always have current going in one direction. It will still pulse, but with each (original) peak of the sine wave (positive and negative inverted to positive) you're closer to what you seek. A capacitor across the input should sustain any "ON" cycle you want, but all you're doing is just turning the light on when music plays. When it drops down below a threshold the lights would go off. I don't see any real appeal in that.

I've messed with audio pulsed lighting using a laser diode and a rotating mirror. As the music pulses the laser and as it sweeps in circles you get the appearance of dots moving one way or the other, depending on the frequency. Low frequencies appear more like dash lines than dots. Higher frequencies appear more as dots than dash lines. It's one of those projects I started years ago and have never finished. And of course, my work takes me away from home often so I don't always get to sit in my laboratory and tinker with the toys.

I also remember light boxes with colored lights behind a diamond pattern light defuser. The lights pulsed with the audio amplitude. So when things got loud the lights came on bright. Softer music produced lower levels of light output. Quiet - or absent audio produced no light output at all. And the lights were not LED,s they were incandescent Christmas lights.
 

Thread Starter

edgar peace

Joined Nov 28, 2018
16
Hello,

Sound will consist of a lot of peaks.
Perhaps an envelope detector in stead of the single diode might help:
https://en.wikipedia.org/wiki/Envelope_detector

Bertus
So it's RC circuit in parallel with my SSR inputs (that's after my diode detector). This will not attenuate my input signal at all. Have to experiment on the RC values so quiet portions will immediately turn off the lights. Have to try it later and i'll post the result. Thank you very much.
 

Thread Starter

edgar peace

Joined Nov 28, 2018
16
I'm going to take a stab at a guess as to what your goal is: I'm thinking you want the lights to react to the amplitude of the audio wave form. At least that's what I'm thinking. If you want to light the light, use an RC circuit to prevent flicker then it pretty much sounds like you just want the light to come on when the music is playing.

One option is that you could go full wave rectification on your audio, then you'd always have current going in one direction. It will still pulse, but with each (original) peak of the sine wave (positive and negative inverted to positive) you're closer to what you seek. A capacitor across the input should sustain any "ON" cycle you want, but all you're doing is just turning the light on when music plays. When it drops down below a threshold the lights would go off. I don't see any real appeal in that.

I've messed with audio pulsed lighting using a laser diode and a rotating mirror. As the music pulses the laser and as it sweeps in circles you get the appearance of dots moving one way or the other, depending on the frequency. Low frequencies appear more like dash lines than dots. Higher frequencies appear more as dots than dash lines. It's one of those projects I started years ago and have never finished. And of course, my work takes me away from home often so I don't always get to sit in my laboratory and tinker with the toys.

I also remember light boxes with colored lights behind a diamond pattern light defuser. The lights pulsed with the audio amplitude. So when things got loud the lights came on bright. Softer music produced lower levels of light output. Quiet - or absent audio produced no light output at all. And the lights were not LED,s they were incandescent Christmas lights.
HI Tonyr1084,
Wow. I understand what you want to achieve is very time consuming and brain twisting (lol) aside from being expensive. I just want to start a very simple project like this and maybe later to more intermediate ones.
Thanks.
 

Tonyr1084

Joined Sep 24, 2015
3,625
I understand what you want to achieve is very time consuming and brain twisting
Actually very little money has gone into this. I've started with an old CD player. Took the motor with the long shaft and disk platen. Cut away the excess plastic then hot melt glued a small round mirror to the surface of the platen. Made sure it was not flat. A flat mirror will not produce a sweeping circle, whereas a mirror slightly tilted and spinning will shine the laser light on the wall creating a circle. Next, you just modulate the on and off signal to the laser diode and you get the pulses. Depending on the speed of the motor and the audio frequency you get your effect. Quite simple.

Many many years ago we built something like it using an old album mounted on a motor shaft. With crude brushes we made contact with the spinning album. On the album were mounted several standard diodes. They were pulsed directly from the audio output of an old car stereo. Depending on how fast the record rotated you got your effect. The problem with that was brush noise. Pink Floyd never looked so good. (no mis-typing) That and a little (not advocating) wacky tabacky and you had an evening full of - well - a full evening of something. I just don't remember what we were laughing at.

Watching audio frequencies that overlapped. Some dots moving clockwise, some moving counter clockwise. Large dashes punctuating through as the base notes played - it all made for quite the entertainment. A motor, an old album, some LED's, some home made brushes and you're off. Not a real expense there either.

I even drew up plans for a digital version, even bought the LED's for that. So far I've hardly tinkered with any of it.
 

MisterBill2

Joined Jan 23, 2018
3,963
To avoid the flickering light effect the simplest way will be to put a capacitor across the SSR DC control terminals. The low impedance of the speaker drive circuit will quickly charge the capacitor to the audio voltage peaks, while the somewhat higher impedance of the SSR will discharge it a bit more slowly. Use a low-leakage capacitor, start with possibly 4.7mFD, rated at least 25 volts, or 50 volts rating would be better. If that is not adequate then add more capacitance. There are a lot of other ways to achieve the effect that you want, but probably none of them are simpler. You may also try connecting to the 16 ohm output of your amplifier to make it more sensitive, if the amplifier has multiple impedance connections.
A funny thing is that many years ago, just exactly that flickering effect was called a color organ and there were dozens of circuits published to achieve the effect. There were three frequency ranges, bass, midrange, and treble.
 

MaxHeadRoom

Joined Jul 18, 2013
19,145
The colour organ is usually a little more sophisticated than the OP.s suggestion!!
They often used a FFT (Fast Fourier Transform) many fairly recent designs using a Picmicro etc.
Max.
 

Tonyr1084

Joined Sep 24, 2015
3,625
Capacitor voltages on audio sources: CAUTION: I've seen upwards of 90 volts on an audio output (going to the speakers). If your audio source is from speaker outputs then you're going to need a substantially higher rated voltage capacitor than 50 volts.

If you're using a pre-amplified source then that's going to be much lower, and off hand I don't know what kind of voltages you might see there. So I'd suggest you discover what the true peak voltage out on your audio source is before you throw a capacitor on it. Possibly blow up the capacitor, and maybe even your audio equipment.

Way back when I was a teen - I mean WAY back, I had a car stereo and a 12 volt transformer and one of those large finned rectifiers. I figured 12 volts rectified should play the radio just fine. Boy was I surprise with the hum. Someone exactly as much experience as I had then told me to put a filter capacitor on it. Didn't know what he meant so I experimented with a 16 volt electrolytic cap on the output. No change - the radio had a horrible hum. So I tried it on the input side of the transformer - yes, a 16 volt cap on 120 VAC. When I flipped the switch that cap completely disappeared. Not like the Philadelphia experiment - no - that thing blew up and I could not find a single piece of it. Fortunately for me I wasn't in the path of disappearance. Caps can explode if you apply the wrong voltage to them. So KNOW what voltages you're working with before you slap something on there.

Take my advice and you may never thank me. Ignore it and you may regret having done so.
 

MisterBill2

Joined Jan 23, 2018
3,963
The colour organ is usually a little more sophisticated than the OP.s suggestion!!
They often used a FFT (Fast Fourier Transform) many fairly recent designs using a Picmicro etc.
Max.
Bertus is totally correct! None of those color organs published in Popular Electronics back in 1967 had microcontrollers or even op amps. Just three filters, except for the really exotic ones that had a bass channel. Why use a bulldozer and chainsaw when a leaf rake will do the job very well.
AND, Tony, the SSR is rated up to 35 volts on the control input, according to the original post. Thus a 50 volt cap is conservative and a 4.7 mfd 16 volt cap should not have any problem. The AC from the mains feed is typically 120 volts RMS, fused at 15 amps=1800 Watts available before the fuse even starts to worry.
 
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