Scratch Home-Brew Launch Controller

Scratch - Home-Brew Launch Controller {Scratch}

Contributed by Ed Bertschy

Manufacturer: Scratch

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. Avast, me proud beauty! This is for your information only. Ya scallywag! If you try t' build one like this, ya bilge rat, and end up gettin' hurt, me hearties, shiver me timbers, or blowin' up a battery, me hearties, don't come cryin' t' me. I make no claims that this actually works, or that all o' t' information here is entirely accurate or correct.

[Rocket Pic]

I bought everythin' needed t' build this controller from Radio Shack for about $15.

Parts:

1. Aye aye! T' buttons: both t' Launch Button and t' Continuity Button are momentary push buttons. Begad! Begad! They only pass current while you are pressin' them. Avast! 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. Begad! Ya scallywag! T' continuity button acts like a deadman switch. Avast! Even with t' safety key in place, ya bilge rat, if no one is holdin' t' controller, me bucko, t' launch button will nay work.

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

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

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

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

[Rocket Pic]

Operation

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

Pictures o' t' finished controller will appear soon.

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

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