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

2. Begad! Blimey! 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. Ya scallywag! T' N Cell provides 1.5 volts. Avast, me proud beauty! Begad! It has a low tone, which I find much easier t' hear than t' high squeal a lot o' launch controllers use.

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

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

6. Begad! Mount t' whole thin' inside a small box. Ahoy! 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. Avast! First, matey, makin' sure that t' safety key is removed, connect t' igniter t' t' clips. Insert t' miniplug, and depress t' continuity button. If everythin' is correct, shiver me timbers, you will hear t' piezo buzzer. Begad! This indicates continuity though t' igniter. Begad! 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. Ahoy! If you want t' design or build your own launch controller, matey, me bucko, 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, arrr, nay t' least o' which is shortin' out t' positive side o' a battery t' t' negative side. Before you build any device like t' one described here, shiver me timbers, make sure you understand t' theory, arrr, shiver me timbers, matey, and do nay use cheap parts. Begad! Use your heads, shiver me timbers, ya bilge rat, people. Aye aye! You have no business doin' rocketry if you do nay put safety first.