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. Blimey! Arrr! This is for your information only. Begad! If you try t' build one like this, and end up gettin' hurt, or blowin' up a battery, me hearties, don't come cryin' t' me. Arrr! I make no claims that this actually works, me hearties, me bucko, 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. Well, blow me down! They only pass current while you are pressin' them. Aye aye! T' type o' button t' avoid is a Push-On/Push-Off type button. Well, blow me down! You also do nay want a toggle switch or rocker switch. T' continuity button acts like a deadman switch. Even with t' safety key in place, me bucko, if no one is holdin' t' controller, ya bilge rat, t' launch button will nay work.

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

3. Begad! Piezo Buzzer: this needs 1 t' 3 volts t' operate. Begad! T' N Cell provides 1.5 volts. Well, blow me down! It has a low tone, shiver me timbers, ya bilge rat, which I find much easier t' hear than t' high squeal a lot o' launch controllers use.

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

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

6. Begad! Blimey! Mount t' whole thin' inside a small box. I put t' Launch Button and Safety Key on top, and t' Continuity Button on t' side.

Operation

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

Pictures o' t' finished controller will appear soon.

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