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View Full Version : Thinking Grinch to control strobe from disposable camera



rkhanso
11-15-2009, 12:02 AM
I have Ren SS24's and am not familiar with the Grinch board. (though, I'm not that knowledgeable about the SS24, either)

Here's what I want to do....
I have flashes dissected from disposable cameras. I want to power them with a separate power supply, but need a way to control them using Vixen. What I need to do is place a 'short' across two pins on the flash board to make it fire and get re-charged.

I'm sure a Grinch board will work for this purpose just fine - but do I need to use a SSR (to place a short across those pins)? Or, will the output from the Grinch be enough to place a short across the 2 pins? Do I really need the relay? Or is a relay not the device I need? It's just a remote, vixen controlled short circuit that is needed to fire the flash. If a relay or other part is needed, I have no idea what type, etc.

I searched for 'disposable camera' in the Grinch forum and came up blank. Anyone do this before, or can help out?

P. Short
11-15-2009, 01:20 AM
It depends on how much of a 'short' that you need, and what voltage would be seen across if when it's in the open state. Does the resistance need to be on the order of tens of ohms, ohms, or something smaller.

NogginBoink
11-15-2009, 11:35 AM
From reports I've read elsewhere, there are several different designs of disposable camera which would have different answers to Phil's questions. I think a goold old-fashioned mechanical relay is probably the best bet for triggering the flash.

jmksparks
11-16-2009, 02:22 AM
From reports I've read elsewhere, there are several different designs of disposable camera which would have different answers to Phil's questions. I think a goold old-fashioned mechanical relay is probably the best bet for triggering the flash.

Thats the way I had to go, 5v mech relay. Changed the opto on a ssr to op a TIP 120. Did not want to trust the ULNs on the Olsons

rkhanso
11-16-2009, 10:00 AM
A friend of mine said a MOSFET should work - connected to the switch connectors on the camera flash board.
I didn't see on the Grinch wiki page what the voltage output of each channel is, but I'm assuming it's at least 3.5v to 5v, right?

NogginBoink
11-16-2009, 06:51 PM
The Grinch requires an outboard power supply, which should be 5V. The output from the Grinch will be whatever voltage the power supply is. (Use a spare hard drive connector from your computer and pull 5V from that.)

I'm sure you could get a MOSFET to work for a particular disposable camera model, but again, I've seen reports that there are significant differences between the schematics of various models. Some may even present high voltage at the trigger inputs. For instance, this model (http://www.increa.com/reverse/dc/) appears to have 300V across the trigger button. I don't know if that would damage a MOSFET.

Also note that MOSFETs are going to be sensitive to polarity and I don't think they'll work at all if you wire 'em up backwards.

A mechanical relay won't have the polarity problem, but contacts probably won't be rated to 300V, either. (And I'm not sure what the insulation for CAT5 cable is rated to, either.)

It's a fun problem. MOSFETs can be had for cheap. I encourage you to play around and post back with your results.

IdunBenhad
11-16-2009, 09:22 PM
Hi:
Consider using a K74 relay board. It has 8 channels, is reasonable in price and can be easily controlled with Vixen and a parallel port on your computer.

The relays will handle the short on the strobes with no problem. I've done it, although right now I will not be using strobes in my display.

Good Luck

Idun

rkhanso
11-17-2009, 10:11 AM
Hi:
Consider using a K74 relay board. It has 8 channels, is reasonable in price and can be easily controlled with Vixen and a parallel port on your computer.

The relays will handle the short on the strobes with no problem. I've done it, although right now I will not be using strobes in my display.

Good Luck

IdunIdun, I like that idea - I think it would work perfect.
Does anyone have a board layout for Home Etching one of these relay boards? Or someone have a spare board laying around they'd like to sell?

IdunBenhad
11-18-2009, 12:54 PM
Hi:
The complete kit is available here:

http://www.electronics123.com/s.nl/it.A/id.446/.f;jsessionid=0a0105531f438a736c61866e498f904ae120 f6d31626.e3eSc3uRax8Te34Pa38Ta38Pc350?sc=8&category=35

Good Luck

Idun