Old Flash New Camera: Trigger Voltage for the Nimslo Opti-Lite / Nikon / Fuji X100s?

I recently bought a Nimslo Opti-Lite external flash, (comes with the Nimslo 3D film camera). I'm aware that many old flashes are dangerous to use on new electronic cameras because of excessive trigger voltage. The cameras I intend to use it on are my Nikon D7000 and Fuji X100s. I have heard Nikons can handle a decent amount of trigger voltage, (some where around 6v) and also recall the X100s having a bit less (around 4), that is if I remember correctly. I know you that I can buy a flash voltage protecter but would not want to if I do not have too.

Primarily interested with Dual Flashes, I was also looking into lights like the Nishika Twin Light 3010 and the Albinar 100MDT-Twin Bounce Flash.

I have an old flash cable and was also wondering if I were to use that, would it alter the voltage the camera receives, making it safer.

I also have a pair of wireless speed lights and was wondering if the old flash could somehow damage the receiver that it's plugged onto?

If anybody can give me any information about voltage for the Nimslo, the Albinar, the Nisika, other similar flashes, voltage protectors, alternative solutions, etc… I would really appreciate it!

Added (1). I really appreciate all the help so far from everyone! Thank you very much for all of the advice and suggestions. I will definitely look into buying a voltage reducer and will also try to test the voltage on the Nimslo.

Here is a link to some of the trigger voltages

http://www.botzilla.com/photo/strobeVolts.html

As you can see, All the Nikon flash units fall under 6v, so finding a good used one is another option.

What you will also see is that the Nimslo Opti-Lite is NOT listed. This means you will have to make your own measurement.

You can do that using a standard Multi-meter and activate the "hold" feature so that the trigger voltage can be captured during your tests

Firstly - a 'decent' amount of trigger voltage is around 6V - for a modern flash designed for digital cameras, however old flashes designed for film cameras have trigger voltages of several hundred volts which will fry a DSLR or bridge camera. Using a flash cable will make zero difference. You need a Wein 'safe sync' if you intend to connect a high trigger voltage flash directly to your digital camera (either via a cable or on the hotshoe).

That flash model is not listed here;
http://www.botzilla.com/photo/strobeVolts.html

so no way of telling trigger voltage unless you measure it yourself with a multimeter.

The Nishika Twin light 3010 is NOT safe - it has a trigger voltage of 307V.
The Albinar is reportedly safe with a trigger voltage of just over 3V.

The old flashes will also damage some wireless triggers/receivers (eg RF602's) but Cactus V5 triggers can supposedly take a high trigger voltage.

Edit: rather than take the risk - a cheap, manual flash like the Yongnuo YN560 (what I use) costs around £40 - great guide number, bounce/swivel head, zoom head, fully adjustable from full down to 1/128 power. Why not just buy one of those?

Nikon DSLRs generally handle 250V (this info is on page 275 in your D7000 manual). The Nishika uses 307V for the trigger voltage which is unsafe for your camera.

You can buy an adapter which will allow you to use high voltage triggers with any camera.
http://www.bhphotovideo.com/...oe_to.html