So I was racking my brain to figure out how to incorporate a pwm into my system useing the electronics on my truck i.e. points coil etc.Anyway to no avail.But I found something else lying around the shop and decided to give it a try.Tried to post a photo but my camera isnt working.I found a mechanical device I took off a sign that flashed.It has two sets of contacts and is completely ajustable as far as intervul etc.It works great.Iknow there is a slight risk from the very small sparks created by rhe contacts but I will encase the device in a wood box and I think that will take care of the problem.Part of the reason for using it is it 's free but also having a tough time sorting through what not to buy.It's very cool and works great!I can finally justify not throwing something away.