How-to: remote ignition

[MrCrowley]

I recently made a simple remote ignition circuit for a hybrid cannon. Once you have all the components, the rest is just a matter of soldering so I'll keep this how-to brief.

Instructable:
http://www.instructables.com/id/How-to- ... -spudguns/

Components:
1x Arlec 149 door chime
1x 100uF 10V capacitor (10ML100MEFC6.3X5)
1x 1A 200V standard diode (1N4003)
1x SPDT on/off toggle switch
1x key on/off switch
1x 3V DPDT relay (IM01TS)
1x 100kV stungun

This should work for any door chime circuit I imagine. They're not all 3V but all you'll have to do is change the relay. You also don't have to use a stungun, any similar-operating circuit would suffice as long as it produces a spark when voltage is applied to the circuit.

For people with intermediate or above electronic skills, refer to the below diagrams if required and ignore the rest (diagram credit: dewey-1):



Diagram note: In error, I ordered a normally-closed relay but it doesn't make too much difference, just change contact #2 to contact #4.

Step 1:
Cut the two wires going to the door chime speaker. Find out which one is positive and negative.

Step 2:
Connect the positive and negative wires that led to the door chime speaker to the relevant poles of the 100uF capacitor.

Step 3:
Use another two wires and connect them to the 100uF capacitor, these will lead to the diode. Connect the positive wire from the capacitor to the cathode (-) of the diode and the negative wire from the capacitor to the anode (+) of the diode.

Step 4:
Solder another two wires to the diode and connect the negative wire (which is on the anode of the diode) to contact #8 (on the relay I used, it may be different for you if you use a different relay) and the positive wire from the cathode of the diode to contact #1 on the relay.


Step 5:
Wire the positive wire from the 9V battery used to power the stungun to contact #4 on the relay. Wire the positive wire from the stungun to one contact on the toggle switch. Wire another positive wire from the other contact on the toggle to conact #3 on the relay.


Step 4:
Connect the negative wire from the 9V battery to the stungun.
The other switches in the pictures below are for 'manual' firing.





Edit:
I have provided an update in a post on page four. I changed the circuit and the setup for a few reasons outlined in the post. You may still use the guide outlined in this original post or make the few modifications I have on page four.

As mobile chernobyl correctly states on page three, a circuit like this can be bought of eBay for a similar price to a door bell. However, it already has a built in 'relay switch' so there's much less soldering and electronics required when using that circuit. Simply hook it up to 12V on one side and attach the load (stungun) to the other.

[jackssmirkingrevenge]

What's the possibility of external interference triggering it by accident?

[MrCrowley]

The same model door chime can trigger it, probably any model of the same brand assuming the frequency code is the same (can be changed quite easily). Other branded door bells probably could trigger it also but I'm not sure.

The main reason I'd use remote ignition is for heavy projectiles (recoil). The cannon would be in place and aimed in the correct direction when the ignition safety is switched so I wouldn't be too concerned if someone happened to ring a door bell and set it off with me standing next to it.

[jackssmirkingrevenge]

The cannon would be in place and aimed in the correct direction when the ignition safety is switched so I wouldn't be too concerned if someone happened to ring a door bell and set it off with me standing next to it.

Mossad would be proud

Very neat job by the way, nicely done.

[Crna Legija]

Other branded door bells probably could trigger it also but I'm not sure.

Yep, we bought one for our house when we did a reno and it was setting off our next door neighbours door bell and would sometimes open our own garage door we got a wired one installed to fit that up.

[dewey-1]

Looks great for a nooby in Electronics!
As you get more experienced, you will find ways to compact that modification wiring. (In other words, you learn how "not to" rather than what you did the first time.)

Example: Double sided foam tape or hot glue the relay and capacitor on the receiver PCB first.
Then proceed to wiring of relay:
1. The diode on the coil first, leave the leads long for now.
2. Add capacitor leads next.
3. Add + and - speaker leads.
4. And finally power leads to relay NO contacts.

24 to 22 gauge wire is ample enough. If larger size, then undo weight/stress is put on the fragile relay leads.
Remember this relay is desiged for PCB mounted through holes, not discrete hanging wires.

There is an updated drawing that I posted in the original thread if you would like to update this 'How To" and the Youtube clip.

A safety switch in the transmitter (doorbell button) would alleviate a potential misfire. A simple "jumper" would suffice or a key switch.

I have a similar circuit to control my X-Box that has been in use for about six years and has never had a false signal trip. This is in an urban area.

[RJB INDUSTRIES]

what is the terminal ignition voltage?

[MrCrowley]

Remember this relay is desiged for PCB mounted through holes, not discrete hanging wires.

Yeah that was the tricky thing about the wiring, better than paying another $25 for a larger 3V-32V relay though. I ended up super-gluing wires to the relay or PCB to take the strain off the relay contacts, especially the one which had broken the contact off.

A safety switch in the transmitter (doorbell button) would alleviate a potential misfire. A simple "jumper" would suffice or a key switch.

I was looking in to this briefly but was a little confused. The voltmeter gave a reading of a few volts on any of the four contacts for the momentary switch, when the button was depressed the voltmeter gave a slightly higher reading. Perhaps I screwed up somewhere and didn't pay attention to what I was doing

I had wanted to change the transmitter button, I thought about wiring a new switch directly to the contacts of the existing momentary button.

what is the terminal ignition voltage?

As dewey-1 pointed out, I'm a noob when it comes to electronics so are you talking about the supply voltage for the stungun circuit? If so, it's 9V. If you're talking about what the stungun produces, it's 100,000V.

[dewey-1]

Here is a pictorial of how you could have done the wiring.

You trim the dode leads after everything is soldered.

[MrCrowley]

Smart!

I need some more electrical projects like this, nothing too hard nor expensive but something hard enough that I still learn new things.

[jackssmirkingrevenge]

I need some more electrical projects like this, nothing too hard nor expensive but something hard enough that I still learn new things.

*cough*

*cough*

[MrCrowley]

I'm not even going to entertain that with a rebuttal, we have about 30 pages covering this

Or does this mean you're machining me a much bigger MiniBoy

[jackssmirkingrevenge]

Or does this mean you're machining me a much bigger MiniBoy

This is a genuine offer: make a tracker that works and is reasonably compact, and I will provide the projectile and sabot

[MrCrowley]

Summer holiday electrical project FTW

You're on!

[jackssmirkingrevenge]

Brilliant just one specification, it will be alongthese lines so go for a long and lean design