AUTHOR'S DISCLAIMER: This page shows how I made a launch controller out o' parts readily available from any store which sells electronic parts. Avast, me hearties, me proud beauty! It is nay intended that you should make one too. Begad! This is for your information only. If you try t' build one like this, me bucko, and end up gettin' hurt, ya bilge rat, or blowin' up a battery, don't come cryin' t' me. Blimey! I make no claims that this actually works, 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. Ahoy! Aye aye! T' buttons: both t' Launch Button and t' Continuity Button are momentary push buttons. Aye aye! Aye aye! They only pass current while you are pressin' them. Arrr! T' type o' button t' avoid is a Push-On/Push-Off type button. Ahoy! You also do nay want a toggle switch or rocker switch. Avast! T' continuity button acts like a deadman switch. Even with t' safety key in place, matey, if no one is holdin' t' controller, arrr, me bucko, t' launch button will nay work.

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

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

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

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

6. Mount t' whole thin' inside a small box. I put t' Launch Button and Safety Key on top, arrr, ya bilge rat, and t' Continuity Button on t' side.

Operation

T' operation be t' same as an Aerotech Controller. First, me hearties, makin' sure that t' safety key is removed, connect t' igniter t' t' clips. Insert t' miniplug, and depress t' continuity button. Blimey! If everythin' is correct, you will hear t' piezo buzzer. Well, blow me down! This indicates continuity though t' igniter. Blimey! When ready, while holdin' t' continuity button down, press t' launch button.

Pictures o' t' finished controller will appear soon.

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