Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 63 users online :: 3 registered, 0 hidden and 60 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], D_Hall, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

a different kind of relay for ignition help

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
Sponsored 
  • Author
    Message

Unread postAuthor: jrrdw » Sun Dec 02, 2007 6:59 am

Just wanted to say how ironic it is that the ignitions of old used condensers to asorb eletricity to avoid miss fires. Todays ignitions use condensers to discharge eletricity into the system, and still uses all the same basic parts, except points where removed and replaced with magnetic triggers.

Good luck on your ignition system. You wern't able to find a 5 poll relay?
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: TechnoMancer » Sun Dec 02, 2007 7:20 am

the modern things have even scrapped the magnetic trigger and use a coil on each spark plug and trigger them all electronically!!
  • 0


TechnoMancer
Corporal
Corporal
 
Posts: 64
Joined: Mon Jul 02, 2007 4:58 am
Location: Christchurch New Zealand
Reputation: 0

Unread postAuthor: jimmy101 » Sun Dec 02, 2007 11:46 am

TechnoMancer wrote:that should be right.
if that doesnt work the coil could be connected to pin 4

Techno is right.

This particular suggestion converts the relay into what is called a "buzz coil". You use the "normally closed" (NC) contact in series with the power supply for the relay's coil. When you apply power, the power flows through the NC contact and energizes the relay's coil. This opens the NC contact and closes the "normally open" (NO) contact.

Since the NC contact supplies power to the relay's coil when it opens the relay's coil is turned off. The net results is that the relay will cycle on and off very quickly and the relay buzzes. As long as the trigger switch is closed the relay will continue to cycle.

With a photoflash cap as the main power source for the HV part of the circuit, it probably doesn't matter if the relay cycles on and off as a buzz coil of if it just closes as long as the trigger switch is closed. The first time the NO contact closes you'll probably get pretty much all the energy in the photocap dumped through the NO contact and into your ignition coil.

One problem you might have is that this type of relay is really not designed to handle the very high current and voltage that a photoflash will supply. The electrical contacts inside the relay might get fried pretty quickly. That is why people usually use automotive relays. Automotive relays are designed to carry several hundred amps at 12V. According to the RadioShack, this particular relay is rated at 3 amps, 12 V.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3127
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: Ragnarok » Sun Dec 02, 2007 12:02 pm

I've used a buzz coil to provide the short pulse needed to fire a coilgun more efficiently, but so that when it closed, it shorted the connection across the coil causing it to turn off - a parallel mode. I that setting up so that it was in a series mode didn't work at all.

It was rated at 5A 250V, but it held up against against the higher coilgun currents quite well. It reset itself slowly enough it couldn't pulse again soon enough to negatively affect the armature (projectile) with a second pulse.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: TechnoMancer » Sun Dec 02, 2007 4:33 pm

i was saying that the diagram may not be accurate and so if he wired the cap or coil to the NC contact the thing would be on permanently unless you turned the relay on. so if it doesn't work that way then change the contact
  • 0


TechnoMancer
Corporal
Corporal
 
Posts: 64
Joined: Mon Jul 02, 2007 4:58 am
Location: Christchurch New Zealand
Reputation: 0

Unread postAuthor: TechnoMancer » Sun Dec 02, 2007 4:43 pm

jrrdw wrote:Just wanted to say how ironic it is that the ignitions of old used condensers to asorb eletricity to avoid miss fires.


actually they were used to stop the points from making excess electromagnetic radiation because it interferes with the radio
  • 0


TechnoMancer
Corporal
Corporal
 
Posts: 64
Joined: Mon Jul 02, 2007 4:58 am
Location: Christchurch New Zealand
Reputation: 0

Previous

Return to Combustion Cannon Discussion

Who is online

Registered users: Bing [Bot], D_Hall, Yahoo [Bot]

Reputation System ©'