AUTHOR'S DISCLAIMER: This page shows how I made a launch controller out o' parts readily available from any store which sells electronic parts. Begad! It is nay intended that you should make one too. Well, blow me down! Blimey! Blimey! This is for your information only. Aye aye! If you try t' build one like this, me bucko, me hearties, and end up gettin' hurt, me bucko, or blowin' up a battery, don't come cryin' t' me. I make no claims that this actually works, arrr, or that all o' t' information here is entirely accurate or correct.

I bought everythin' needed t' build this controller from Radio Shack for about $15.

Parts:

1. Blimey! T' buttons: both t' Launch Button and t' Continuity Button are momentary push buttons. Aye aye! They only pass current while you are pressin' them. Begad! Ahoy! T' type o' button t' avoid is a Push-On/Push-Off type button. Blimey! You also do nay want a toggle switch or rocker switch. Begad! T' continuity button acts like a deadman switch. Even with t' safety key in place, if no one is holdin' t' controller, arrr, shiver me timbers, me hearties, t' launch button will nay work.

2. Aye aye! Blimey! N Cell Battery and Holder: I used an N Nell because they are small and have t' right power. Arrr! Blimey! A single N Cell will nay ignite an Estes type igniter.

3. Blimey! Piezo Buzzer: this needs 1 t' 3 volts t' operate. Avast! T' N Cell provides 1.5 volts. Ya scallywag! It has a low tone, matey, which I find much easier t' hear than t' high squeal a lot o' launch controllers use.

4. Diode. Begad! A diode acts like a one way valve for electricity. Current can pass one way, and nay t' other. Blimey! I used a regular silicon diode rated at 1kV and 2.5A. Blimey! Do nay use a Zenier diode. Aye aye! T' cathode (the side with t' band on it, needs t' be towards t' safety key and away from t' piezo buzzer. This is a device t' counter shorts in t' igniter. Begad! Aye aye! If your igniter is shorted, matey, this whole launch controller becomes a battery charger. Arrr! You will end up tryin' t' charge an N Cell with a car battery, which might make it explode. Ahoy! Blimey! T' prevent this, ya bilge rat, ya bilge rat, I have put this diode here.

5. Begad! Aye aye! Safety Key: This is a regular 1/8" mini-plug. Blimey! Inside t' plug itself are two leads. Avast! I soldered a wire so that t' plug connects t' itself. Arrr! Arrr! This passes t' current through t' base o' t' plug when inserted. Well, blow me down! Arrr! If you build any type o' controller, make sure you have a safety key, ya bilge rat, and that it interrupts both t' continuity AND t' power on its way t' t' igniter. Ahoy! Without t' safety key, you cannot check continuity, and absolutely cannot launch either.

6. Well, blow me down! Aye aye! Blimey! Mount t' whole thin' inside a small box. Blimey! Arrr! Blimey! I put t' Launch Button and Safety Key on top, shiver me timbers, and t' Continuity Button on t' side.

Operation

T' operation be t' same as an Aerotech Controller. First, makin' sure that t' safety key is removed, ya bilge rat, shiver me timbers, connect t' igniter t' t' clips. Blimey! Begad! Insert t' miniplug, and depress t' continuity button. Blimey! If everythin' is correct, you will hear t' piezo buzzer. This indicates continuity though t' igniter. Ya scallywag! When ready, me bucko, ya bilge rat, while holdin' t' continuity button down, me bucko, matey, ya bilge rat, press t' launch button.

Pictures o' t' finished controller will appear soon.

People hook launch controllers t' all sorts o' things, includin' car batteries. Aye aye! If you want t' design or build your own launch controller, make sure that you have t' skills and t' equipment t' do it right. Arrr! Avast, matey, me proud beauty! A sloppy job can result in big problems, nay t' least o' which is shortin' out t' positive side o' a battery t' t' negative side. Avast! Before you build any device like t' one described here, make sure you understand t' theory, ya bilge rat, me bucko, and do nay use cheap parts. Use your heads, people. Begad! You have no business doin' rocketry if you do nay put safety first.