making a pyro firing unit

[tonymaslen]

I am looking into the practicalities of making a Pyro Flash unit, from parts. Does anyone has any schematics etc or useful information about creating one of these?

[Andrew C]

I am looking into the practicalities of making a Pyro Flash unit, from parts. Does anyone has any schematics etc or useful information about creating one of these?

<{POST_SNAPBACK}>

Really?

 

The ABTT CoP has/had a few schematics in it.

[bruce]

www.bigclive.com is your friend.

 

Bruce.

[tonymaslen]

Cheers, for the help.

[Jivemaster]

Most projects are cheaper to buy than make unless you want something really special, yet simple. Hand making a case/box usually costs the same as buying the item trade.

 

other than that, a LeMaitre igniter tends to be 20 ma no fire and 500ma all fire so set the "test" current to say 5ma and the fire current to an amp or so.

 

Estimate the number of series igniters (at 1.5 ohms) you will want to fire at once and the resistance of the cable length Allow about 1.5volts per ohm of circuit, to get a good fire current. I've seen a PP3 used for small scale work, small 12V SLA batteries in mid scale work and 500 - 800volt capacitor discharge in really large scale projects ( Search for "shrike exploder"), Smaller cap discharge supplies can be canibalised from the electronic flash of a disposible camera, mind the 150 - 300VDC

 

Think SAFETY think KEYSWITCH, Think FAILSAFE

[ChrisD]

Also think don't let anyone else test it with you unless they know exactly how the circuit works. I once heard of a guy who got a pyro in the eye and died from the heart attack the shock of having a molten eyeball caused him. This was because someone who didn't know what they were doing was playing with his custom build controller.

[tonymaslen]

Yeah I am well aware of the dangours of not putting fail safes into the system, (ie key switch) and only alowing myself to test the units.

[Jivemaster]

Designing safety into the product is essential. Make sure you know what all the buttons will do under ALL circumstances. 100% fire when you need it 100% no fire when you need that.

[tonymaslen]

;) 100% fire when you need it 100% no fire when you need that.

Totally!

[paulears]

I built one based on bigclives design about 4 years ago. Works reliably every time. One thing about the buttons. I used fruit machine buttons - the mtbf for these is very high due to the usual use they get! I decided against a keyswitch and used one of these.

http://www.limelight.org.uk/switch.png

 

big, chunky and has great holes where a proper padlock can be fitted. You have to make a conscious effort to turn it on.

 

I'll post a pic later

[mac.calder]

The problem with something like that is that it can be left armed. If you are using a key switch it should only be removable in the OFF position (and idealy, if you are using a digital system, should check that it IS in the off position before starting up)

 

I have been wanting to build one for a while, but finding a key switch with the specs I want is not easy.

 

Pos 1 - Open

Pos 2 - Input 1 to the output, key not removable (or idealy, springload back to pos 1)

Pos 3 - Input 2 to the output, key not removable

 

In fact most of the key switches are key removable in any position.

[tonymaslen]

the site does say that RS supply a key swith that the key can only be removed in the off position.

 

how ever I have not checked the RS site to see if these are still available

[timpman19]

yes they are still available , I checked today, after buying all other components from Maplin

[JimWebber]

We have always used a key-switch that can only be removed in the off position, many many times for EMCON (Emission Control) of radio equioment. We usually buy from RS, but many suppliers out there do them.