stef35
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Need some help for using triac with a raspberry

Fri Feb 13, 2015 9:22 pm

i try to trigger flash light with a raspberry
i guess i need to use a triac for this, but i could not find any tuto, schemes.

thanks for any links that could help me to connect the triac to raspberry and how to use it

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aTao
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Re: Need some help for using triac with a raspberry

Fri Feb 13, 2015 9:37 pm

Triacs are normally used to switch high voltage and medium current. A flashlight almost certainly will not need a triac. Just a mosfet will do and many of the interface circuits posted here will do. It will be the same as a relay driver.
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jimallyn
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Re: Need some help for using triac with a raspberry

Fri Feb 13, 2015 9:40 pm

Can you give us more specific information on what you are referring to as a "flash light"? What you need to trigger your light will vary depending on exactly what kind of light you're talking about.
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mahjongg
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Re: Need some help for using triac with a raspberry

Fri Feb 13, 2015 9:58 pm

You will need to use an optically isolated triac (photo-triac) not using an optically isolated triac may damage your PI!

stef35
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Re: Need some help for using triac with a raspberry

Sat Feb 14, 2015 9:47 am

thanks for your replies, guys

to be more specific, i would like to use a pack of 4*50W lights, to trigger flash lights as you could see in band concert.

at the moment, i have tried with RF power socket but there is too much latency between switch on/off.
I guess i would dhave the same behaviour with relay, as it is not their purpose to be switched on/off very quickly.

I was said triac could do the job, but i do not know how to wire it to the raspeberry and how to trigger it.
Thanks again

stef35
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Re: Need some help for using triac with a raspberry

Sat Feb 14, 2015 9:51 am

could you tell me if P11N60 is a photo triac?
thanks
mahjongg wrote:You will need to use an optically isolated triac (photo-triac) not using an optically isolated triac may damage your PI!

jimallyn
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Re: Need some help for using triac with a raspberry

Sat Feb 14, 2015 8:18 pm

stef35 wrote:could you tell me if P11N60 is a photo triac?
No, it is not. It's a high voltage power mosfet. It will not work for switching AC power, only DC power.

Are you planning to use standard incandescent bulbs? Xenon flash tubes? LEDs? You still haven't given us enough information to determine what you need to use. If you really want a good flash, you should probably use xenon flash tubes, also known as "strobe lights." They are quite bright, and produce a very short duration flash.
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aTao
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Re: Need some help for using triac with a raspberry

Sun Feb 15, 2015 12:07 pm

stef35 wrote:thanks for your replies, guys

to be more specific, i would like to use a pack of 4*50W lights, to trigger flash lights as you could see in band concert.

at the moment, i have tried with RF power socket but there is too much latency between switch on/off.
I guess i would dhave the same behaviour with relay, as it is not their purpose to be switched on/off very quickly.

I was said triac could do the job, but i do not know how to wire it to the raspeberry and how to trigger it.
Thanks again
Stage strobes have changed a bit since I were a lad. Used to be you hit the button, the strobe flashed. Now stage lighting is all DMX and it dosent have the speed for rapid flashing. If you want a single synchronous pulse then the lighting desk send a single flash command, latency is quite high but within gig allowances, lets face it if you are at the back of the hall then the sound is many milliseconds late anyway. For higher flash rates then the desk sends a speed signal and the strobe does the rest.
The strobe tubes have 3 connections, 0V, power and trigger, you put many kV across the power and 0V then a small (10s of V) signal on the trigger will cause the flash. For strobes that arent required to flash frequently a charge pump charges a capacitor to the many kV. For strobes that need to flash more rapidly the the HT PSU is a whole different ball game.

Incandescent lamps never really cut it as a strobe and LEDs dont really have the power.
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stef35
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Re: Need some help for using triac with a raspberry

Sun Feb 15, 2015 6:33 pm

At the moment i was thinking about simple led staff.
I have tried with a small led connected to a gpio and latency was ok. It is why i think problem comes from RF.
Maybe a relay could do the job? Instead of a triac that seems to be more difficult to use with raspberry....

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mahjongg
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Re: Need some help for using triac with a raspberry

Sun Feb 15, 2015 7:48 pm

Photo triacs are as simple to control as controlling a LED (because you are actually controlling a LED).

You can use something like this http://www.vishay.com/docs/83628/il4116.pdf to control light loads directly, or trigger a bigger triac with it (see data sheet how). The pre-built commercially available device is called a "photo relay".

Note, if you think you can handle mains AC, then you can't, mains can kill!

ask a certified electrician to help!

stef35
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Re: Need some help for using triac with a raspberry

Sun Feb 15, 2015 8:14 pm

Thanks for your reply.
I m a bit confused. Is that so dangerous? A photo triac is just like a switch power, no ? Anyway i need to dig a little bit before trying something, for sure. Thanks
mahjongg wrote:Photo triacs are as simple to control as controlling a LED (because you are actually controlling a LED).

You can use something like this http://www.vishay.com/docs/83628/il4116.pdf to control light loads directly, or trigger a bigger triac with it (see data sheet how). The pre-built commercially available device is called a "photo relay".

Note, if you think you can handle mains AC, then you can't, mains can kill!

ask a certified electrician to help!

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davidcoton
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Re: Need some help for using triac with a raspberry

Sun Feb 15, 2015 10:31 pm

stef35 wrote:Thanks for your reply.
I m a bit confused. Is that so dangerous? A photo triac is just like a switch power, no ? Anyway i need to dig a little bit before trying something, for sure. Thanks
mahjongg wrote: ... Note, if you think you can handle mains AC, then you can't, mains can kill!

ask a certified electrician to help!
Yes it IS that dangerous. Yes a triac is like a switch. Both triacs and mains switches are dangerous if you don't understand what you are doing. You must use adequate wiring, properly enclosed preferably in a plastic case, with no metal bolts etc. from inside to outside. If you use a metal case, it must be properly connected to earth (ground), and no possibility of contact between your electronics (including the Pi), or mains wiring, to the case. As far as possible the design must stay safe even when something goes wrong. As mahjongg said, "ask a certified electrician to help!" (Personally I prefer qualified and registered electricians!)
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stef35
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Re: Need some help for using triac with a raspberry

Mon Feb 16, 2015 8:37 am

I 've just found something intersting on the web
http://www.powerswitchtail.com/Pages/Po ... ackit.aspx

Ok, it is less homemade but it is definitely safer :D

Thanks anyway for your advises, guys

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