Sync Trigger Button Circuit explanation

[Robino_J]

I would like to build the Sync Trigger Button shown in the DSMC Operation guide but I'm not too sure how to read the circuit shown.

I got the parts but I need help figuring out where to connect and solder everything:

AA Battery Pack (for 2 batteries)
Push button toggle switch
100ohm 1/4 watt resistor
68 ohm 1/4 watt resistor
10uf electrolytic capacitor
10vLED 1.7V, 20mA
Female BNC connector

Has anyone built this? I would like a little help diagram on how to put this together.

 

[Dave Winder]

I would suggest some shrink tubing also. Its not too bad. You can put the 100 ohm on the end of the red battery lead (assuming you have battery holder) and solder other end to one side of the switch. Cover all that with shrink tubing. Connect the longer lead of the two on LED to the other side of switch, also with a piece of wire to reach the BNC center conductor in parallel. Again with shrink tubing on that joint. You need check whether your LED already has a resistor. If so, then you can skip the 68 ohm. Put 68 ohm on short lead of the LED. Put the negative lead of capacitor (you should see negative sign on the casing) and a wire to the outer conductor of the BNC. Solder other lead to center conductor along with the wire from switch. Lastly tie up the black lead from battery pack, the remaining lead of 68 ohm, and the wire from outer side of BNC all together and you're done. be sure to protect all the bare leads with shrink wrap.

Hope that helps

 

[Robino_J]

Thanks so much Dave! Exactly what I needed.

Thanks again -

 

[Dave Winder]

Also note the capacitor does not have to be at the BNC. You can picture sliding it left in the diagram and attach it at the switch along with LED and wire to BNC. Makes no difference here. Probably easier to build it that way actually, as you will just have two wires to the BNC and leave the other stuff somewhere else. Just be sure to get the polarities correct on LED and capacitor. Let us know how it works out.

 

[Robino_J]

Edit: I found a 68ohm. Back on track!


I thought I had a 68ohm 1/4 resistor but I don't...

Which other her resistor could I use for the LED? Would a 180ohm or greater 1/8 watt work?

 

[Robino_J]

Success!

It's not the prettiest thing but it works great. The leads outside the box are for my custom switch that goes on my Moviola. I'm converting one of my Moviola into 35mm scanner to be used with Dragon. I get around 4.2K resolution for @ 4perfs.

*** Could not have done the trigger without you Dave, thanks so much. ***

Pictures below (sorry for my foot creeping in)

 

[Dave Winder]

Nice! Glad to help.

 

[Robino_J]

Sometimes the trigger "triggers' multiple frames instead of a single one. Any ideas on why it would do that?

 

[ericyoung]

Sometimes the trigger "triggers' multiple frames instead of a single one. Any ideas on why it would do that?

Google "switch bounce" or "switch debounce".

 

[Robino_J]

Google "switch bounce" or "switch debounce".

Thanks Eric - that's exactly what I needed. I ended up building a little box with an arduino board and a little circuit that holds a debouncer code. My Dragon is triggering single frames every time!

Here's the first test scan I did with the Exorcist trailer, it's not stabilized / cropped (that's why the optical soundtrack is in there) and I still have work to do with the optical path but it gives an idea.

Lot's of text at the beginning but when it kicks in- it KICKS in!

https://vimeo.com/136450002
password: 35mm