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! Blimey! It is nay intended that you should make one too. This is for your information only. Begad! Blimey! If you try t' build one like this, shiver me timbers, me hearties, me hearties, and end up gettin' hurt, or blowin' up a battery, don't come cryin' t' me. Begad! Avast, me proud beauty! I make no claims that this actually works, matey, shiver me timbers, 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. Avast, me proud beauty! Begad! 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. Arrr! T' type o' button t' avoid is a Push-On/Push-Off type button. Arrr! Begad! You also do nay want a toggle switch or rocker switch. Avast, me proud beauty! T' continuity button acts like a deadman switch. Begad! Even with t' safety key in place, if no one is holdin' t' controller, 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. Aye aye! Avast! 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. Ahoy! Blimey! T' N Cell provides 1.5 volts. Avast! 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. Begad! A diode acts like a one way valve for electricity. Ahoy! Current can pass one way, and nay t' other. Ya scallywag! Ahoy! I used a regular silicon diode rated at 1kV and 2.5A. Ya scallywag! Blimey! Do nay use a Zenier diode. Ahoy! T' cathode (the side with t' band on it, arrr, ya bilge rat, needs t' be towards t' safety key and away from t' piezo buzzer. Well, blow me down! This is a device t' counter shorts in t' igniter. Begad! If your igniter is shorted, this whole launch controller becomes a battery charger. Begad! You will end up tryin' t' charge an N Cell with a car battery, ya bilge rat, which might make it explode. T' prevent this, shiver me timbers, I have put this diode here.

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

6. Mount t' whole thin' inside a small box. Avast, me proud beauty! Blimey! 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. Avast, me proud beauty! Aye aye! First, ya bilge rat, makin' sure that t' safety key is removed, me bucko, connect t' igniter t' t' clips. Arrr! Well, blow me down! Insert t' miniplug, matey, and depress t' continuity button. Aye aye! Begad! If everythin' is correct, me hearties, you will hear t' piezo buzzer. Begad! This indicates continuity though t' igniter. Aye aye! When ready, arrr, me hearties, 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, matey, includin' car batteries. Begad! Avast! 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. Ya scallywag! A sloppy job can result in big problems, shiver me timbers, nay t' least o' which is shortin' out t' positive side o' a battery t' t' negative side. Begad! Arrr! Before you build any device like t' one described here, ya bilge rat, make sure you understand t' theory, me bucko, and do nay use cheap parts. Use your heads, people. Avast! You have no business doin' rocketry if you do nay put safety first.