Hello all . . . update: I tested strobing lights on/off at 25ms for 2>min using a blink sketch w/ Arduino IDE. Unfortunately in a way, there was no issue. I will try again today, but what this means is that it's possibly a glitch with how MaxMSP is communicating over serial to the Arduino. Again, new problem for me as I've been using this methodology for over a decade - but, we shall see.

A good step forward

BTW: Can you send a link to MaxMSP please
the only program I can find that looks likely is a music score software !

 

A good step forward

BTW: Can you send a link to MaxMSP please
the only program I can find that looks likely is a music score software !

MaxMSP is used for light shows. With DMX and it seems other things, so it is probably what the TS means.

 

MaxMSP is used for light shows. With DMX and it seems other things, so it is probably what the TS means.

Ta

switching a relay on / off once every 25 ms, ( just over one cycle of 50 Hz )
seems very quick to me !

 

Ta

switching a relay on / off once every 25 ms, ( just over one cycle of 50 Hz )
seems very quick to me !

I agree, it should be MOSFETs or triacs (or thyristors) but apparently this is how he's done it.

 

I agree, it should be MOSFETs or triacs (or thyristors) but apparently this is how he's done it.

Just wonder how long a relay would last switched at that speed
How many open / close cycles are they rated at ?

Do relays not also take longer than 25 ms to open / close
So switching then that fast sounds to me like that are constantly arking
Wonder what that does for heat and life .
I remember as a kid making a buzzer out of a rely , and wirring the contacts in series with the coil ,
The relay did not last long , but made a great light show of sparks.
Wonder if the UV from that gave me the melanomer ?

 

Just wonder how long a relay would last switched at that speed
How many open / close cycles are they rated at ?

Do relays not also take longer than 25 ms to open / close
So switching then that fast sounds to me like that are constantly arking
Wonder what that does for heat and life .
I remember as a kid making a buzzer out of a rely , and wirring the contacts in series with the coil ,
The relay did not last long , but made a great light show of sparks.
Wonder if the UV from that gave me the melanomer ?

Terribly off-topic: one of my childhood memories is the doorbells and buzzers that were just that, effectively self-switching relates. Those, along with ceramic knife switches, bulb bases, little #14 bulbs, bell wire, and № 6 "Dry cells" served to entertain me for many hours in my single digit years.

Last off-topic post for me.

 

Ha love the stories. A bit more analog, but I can recall dropping a lit match into a full jug of rubber cement as a child. I appreciate thinking outside the relay box (TRIACs + MOSFETs). And yes, I am probably shorting the life of these relays, but the 25ms strobe is just a test. They are being pulsed to music mostly, so its not a solid 25ms strobe as end result. Anyway, back to work XD

 

Ha love the stories. A bit more analog, but I can recall dropping a lit match into a full jug of rubber cement as a child. I appreciate thinking outside the relay box (TRIACs + MOSFETs). And yes, I am probably shorting the life of these relays, but the 25ms strobe is just a test. They are being pulsed to music mostly, so its not a solid 25ms strobe as end result. Anyway, back to work XD

Would strongly suggest that relays are not the switch you need for music lights , way to much arking and noise on the mains .
Look at SSR ( solid state relays )
Or mosfets as mentioned above.

 

Would strongly suggest that relays are not the switch you need for music lights , way to much arking and noise on the mains .
Look at SSR ( solid state relays )
Or mosfets as mentioned above.

Thank you so much, I will give it consideration!

 

Thank you so much, I will give it consideration!

Would strongly suggest that relays are not the switch you need for music lights , way to much arking and noise on the mains .
Look at SSR ( solid state relays )
Or mosfets as mentioned above.

something like this you feel would be more successful? I'd order x2 to get the full 16 channel output I need. https://www.sainsmart.com/products/...DeiuYfXVBmUz1kS99UmzOGPG-34KVIfxoCHKMQAvD_BwE

 

something like this you feel would be more successful? I'd order x2 to get the full 16 channel output I need. https://www.sainsmart.com/products/...DeiuYfXVBmUz1kS99UmzOGPG-34KVIfxoCHKMQAvD_BwE

They look like Solid State Relays
just check they are AC rated for the voltage and current you want,

Have you read up on how the SSR works ?
in particular , some / Most AC ones can only turn on / off for multiples of one AC cycle

 

This, or something like it (which I can‘t seem to find, surprisingly) would be preferable. It s a 4-channel optoisolated triac board. There are two channel versions of this as well.

This one comes from what appears to be a very reputable firm in Sri Lanka(!). This means shipping to the US is ~$22. Though if you need them, I don’t think that’s a show stopper. But they also seem to be the designer/manufacturer.

​

 

This, or something like it (which I can‘t seem to find, surprisingly) would be preferable. It s a 4-channel optoisolated triac board. There are two channel versions of this as well.

This one comes from what appears to be a very reputable firm in Sri Lanka(!). This means shipping to the US is ~$22. Though if you need them, I don’t think that’s a show stopper. But they also seem to be the designer/manufacturer.

View attachment 261857​

Thank you both. Very, very cool. A question: no heat sink needed on the triac packages? And I'm assuming I connect a cut hot wire to both terminals on each load and it connects/disconnects the 120v wire.

 

Thank you both. Very, very cool. A question: no heat sink needed on the triac packages? And I'm assuming I connect a cut hot wire to both terminals on each load and it connects/disconnects the 120v wire.

They do mention that heat sinks can be added to increase load capacity.

 

My first thought was contact welding, but the OP said "the communication stops after 20 seconds" so I had to assume they were checking the output from the uC.

At that point I decided not to post any suggestions because I have tried to help others with these kinds of issues with no luck.

It seems this is the issue. Tonight I was testing the stuff and low and behold one got stuck - and stayed stuck. I cut AC power to the board, and tapped the offending relay with the back of my wire cuters. I heard a "pop" and it works again.

Maybe this is too dangerous of a move, but I'm tempted to go and perform with this rig until TRIACs arrive. If things stick, I can pop the top and just tap the offending relay with a long wooden dowel.

 

It seems this is the issue. Tonight I was testing the stuff and low and behold one got stuck - and stayed stuck. I cut AC power to the board, and tapped the offending relay with the back of my wire cuters. I heard a "pop" and it works again.

Maybe this is too dangerous of a move, but I'm tempted to go and perform with this rig until TRIACs arrive. If things stick, I can pop the top and just tap the offending relay with a long wooden dowel.

I hope you have fusing in the lines,

Re the triacs / SSR solution and heat sinks

the devices on there own, free standing can dissipate an amount of power, i.e. load
but power will be long way below what they can cope with with a heat sink

Double check, REAL careful
if the SSR / Triac you chose, dose it have an insulated Tab ?
some have a metal tab for the heat sink, that's connected to one of the terminals
which could well be mains in your system,

 

something like this you feel would be more successful? I'd order x2 to get the full 16 channel output I need. https://www.sainsmart.com/products/...DeiuYfXVBmUz1kS99UmzOGPG-34KVIfxoCHKMQAvD_BwE

That SSR is rated for 2A maximum for the AC load. That may not be enough for your application...

 

I hope you have fusing in the lines,

Would a glass fuse like so

do the trick? I've never added a fuse, and seeing that I will be connecting around 1.6K watts @ 120v through this ol' box it seems smart. Just to be blunt, where does it go? I've done some reading about not putting it at the ground line, but that was for DC.

 

Would a glass fuse like so

do the trick? I've never added a fuse, and seeing that I will be connecting around 1.6K watts @ 120v through this ol' box it seems smart. Just to be blunt, where does it go? I've done some reading about not putting it at the ground line, but that was for DC.

First, you need to use an inline fuse holder, for safety.

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Second, selecting the fuse is not necessarily going to be simple. First you have to determine the peak load which may happen only when, for example, turning on the lights. (Are these tungsten or LED?). Second you have to decide what sort of continuous current is OK. You might want a slow acting fuse that can tolerate peaks but not sustained excess current, or you might want a fast acting fuse at a level that just means something is wrong.

You need to characterize your load as best you can to make the right decision, then you need to test your choice to make sure you won't have problems with fuses blowing without a reason.

As an aside, you also have to keep extra fuses and a DMM in your kit for shows or you may regret it.

 

Successful showing with the relay box I constructed, thanks in large part to everyone on this thread. The welding of contacts seems to work its self out well enough that I never needed to don rubber gloves and tap relays with dowel. Footage : http://instagr.am/p/Cb1TLBEshbM/