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. Begad! Avast, me proud beauty! This is for your information only. 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. Ahoy! 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. T' buttons: both t' Launch Button and t' Continuity Button are momentary push buttons. Ya scallywag! They only pass current while you are pressin' them. Arrr! T' type o' button t' avoid is a Push-On/Push-Off type button. Begad! Avast! You also do nay want a toggle switch or rocker switch. Well, blow me down! Ya scallywag! T' continuity button acts like a deadman switch. Arrr! Even with t' safety key in place, ya bilge rat, ya bilge rat, if no one is holdin' t' controller, shiver me timbers, t' launch button will nay work.

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

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

5. Begad! Safety Key: This is a regular 1/8" mini-plug. Avast! Blimey! Inside t' plug itself are two leads. Begad! I soldered a wire so that t' plug connects t' itself. Ahoy! This passes t' current through t' base o' t' plug when inserted. If you build any type o' controller, matey, me bucko, 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, me bucko, and absolutely cannot launch either.

6. Aye aye! Mount t' whole thin' inside a small box. Avast! I put t' Launch Button and Safety Key on top, matey, 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, connect t' igniter t' t' clips. Avast! Insert t' miniplug, arrr, and depress t' continuity button. Avast, me proud beauty! Avast! If everythin' is correct, you will hear t' piezo buzzer. Blimey! Avast, me proud beauty! This indicates continuity though t' igniter. Begad! Begad! When ready, matey, while holdin' t' continuity button down, me bucko, press t' launch button.

Pictures o' t' finished controller will appear soon.

People hook launch controllers t' all sorts o' things, includin' car batteries. Avast! If you want t' design or build your own launch controller, matey, make sure that you have t' skills and t' equipment t' do it right. Ahoy! A sloppy job can result in big problems, arrr, matey, 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, make sure you understand t' theory, me bucko, and do nay use cheap parts. Avast, me proud beauty! Avast! Use your heads, people. You have no business doin' rocketry if you do nay put safety first.