Build your own Ghostmaster

[Neal Chaves]

I have decided to "open source" my Ghostmaster invention. The Ghostmaster is a flash fire control system for leaf shutter cameras. The circuit provides for electronic flash synchronization at shutter opening or closing, or a combination of both with two separate optically isolated channels. Powered by its own internal 9V battery, the Ghostmaster can provide protection for any camera from the high synch voltages and currents of older strobes, up to 400V.

The Ghostmaster was patented in 1996, but the patent is now in the public domain. However, after I began production of the product, I refined the circuit for increased reliability and component availability, and I never made these changes public until now.

The current demand for the device is not great enough to warrant quantity production, and there is some hand work involved. Perhaps some of our members might be interested in building the device for themselves. I have a number of the circuit boards on hand, which greatly simplifies construction and miniaturization. All other components are commonly available at electronics suppliers.

You can find complete details by searching US Patent 5,530,320 and I have attached the revised schematic.

Neal

[WayneStevenson]

So what exactly does this do Neal? My understanding of leaf shutters is that they trip the sync as soon as the shutter is fully opened?

So this will enable you to either trigger the shutter once fully open (as would happen without your device), or right when the shutter starts to close (like a rear-curtain sysnc)?

[searover]

I have decided to "open source" my Ghostmaster invention. ...
I have a number of the circuit boards on hand, which greatly simplifies construction and miniaturization. All other components are commonly available at electronics suppliers.

You can find complete details by searching US Patent 5,530,320 and I have attached the revised schematic.

Neal

So Neal, What would you charge for the Circuit Board and Who's box did you design it for? PacTec is just down the street from my shop - any chance its one of theirs? I might get a few sample boxes if anyone is interested in them.

John

[Steve Smith]

Two comments:

1. I can't see the benefit as they can be fired directly from the sync socket.

2. It's possible to make a circuit which fires a flash from an opto-triac without the need for a separate battery. You use the trigger voltage of the flash to charge a small capacitor through a high value resistor then the shutter contacts discharge this into the LED.



Put two (or more) opto triacs' LEDs in series to fire more than one flash - only derive power from one though.


Steve.

[BrianShaw]

So what exactly does this do Neal?

1. A flash fire control system for leaf shutter cameras to manage a single shutter synchronization pulse for a plurality of electronic flash units, said flash fire control system incorporating switch-selectible modes for a plurality of electrically isolated synchronization output triggers to configure said output triggers for either simultaneous and instantaneous triggering of all of the said plurality of electronic flash units upon the opening of said leaf shutter, or the instantaneous triggering upon opening of said shutter for one or more of the said plurality of electronic flash units and triggering upon the closure of said shutter for one or more of the said plurality of electronic flash units, comprising: (bla bla bla... patent material)

[bob carnie]

I dare you to say that again three times fast.

1. A flash fire control system for leaf shutter cameras to manage a single shutter synchronization pulse for a plurality of electronic flash units, said flash fire control system incorporating switch-selectible modes for a plurality of electrically isolated synchronization output triggers to configure said output triggers for either simultaneous and instantaneous triggering of all of the said plurality of electronic flash units upon the opening of said leaf shutter, or the instantaneous triggering upon opening of said shutter for one or more of the said plurality of electronic flash units and triggering upon the closure of said shutter for one or more of the said plurality of electronic flash units, comprising: (bla bla bla... patent material)

[BrianShaw]

Can't... and won't even try for fear to totally embarassing myself. I'd sure like to understand how the said 9v electrons know the point of said triggering or the said closure of the said single shutter sychnronization before informing the said plurality of electronic flash units. All this time and heretofore I thought the said single shutter only made contact at the said full open position of the said shutter leaves.

[Neal Chaves]

I'll try to answer all your questions. The Ghostmaster was originally designed to duplicate the "second curtain synch" effect which appeared on 35mm focal plane shutter cameras in the early 1990s, but do it with most leaf shutters. One day I was working on a Compur shutter and noticed that the shutter contacts broke while the shutter was starting to close but the shutter blades were still wide open. I knew that an electronic circuit could fire a strobe at that point, just as a mechanical automotive ignition dristributor fires a spark plug when the points open. I had a simple circuit working in a few days, but soon encountered a number of problems that had to be overcome.

All mechanical switches bounce, and if the circuit was too sensitive I would get synch at both opening and closing. This produced some interesting effects, so I designed the circuit with two optically isolated channels. Because it has its own power supply, neither of the Ghostmaster sych outputs are polarity sensitve. With two strobes connected, one can have a sharp image of a moving subject with a motion streak and another sharp image at the end of the exposure. Split diffusion and split filtration are simple to accomplish. The Ghostmaster works best with Compur, Prontor, Compound, Copal, Ilex, Kodak and Wollensak X-sych shutters. Seiko shutters may be partially closed when the Ghostmaster synchs, although the Seiko shutters on Mamiya RZ67 synch when wide open.

There are optically isolated "Safe Sych" circuits on the market, like the one from Wein Products Co., but the Ghostmaster requires its own power supply for closing shutter synch so I used that for the optically isolated instantaneous channel. My circuit board is made to fit in the PacTec No. "K-HM" case. If there is interest, I will package a circuit board, parts list and construction tips for $5 plus postage. I sold a great many of these units for $129 and wholesaled them for $75 to suppliers like Flash Clinic in New York for $75. It received a rave review from a certain Shutterbug Magazine editor who is now doing life without parole in Lynchburg Federal Pen. I gave a two year warranty and none were ever returned.

[coisasdavida]

It received a rave review from a certain Shutterbug Magazine editor who is now doing life without parole in Lynchburg Federal Pen.

I completely missed this when it happened. He has a website up in his defense. Complicated stuff.

[Neal Chaves]

Here is a photo of the two versions I made, the monoplug and the H-type (household, Honeywell). You can see two female PC sockets on the lower left side. The top PC is an optically isolated instantaneous synch. The lower PC is switched to instantaneous or delay by the slide switch, as is the monoplug and the H-type plug. Input from the camera shutter goes in the phone jack or the H receptacle. A test switch simulates shutter fash contacts. These units are built in the PacTec "K-HM" case.