| Manufacturer: | Scratch |
This page describes t' how t' build a very small (1.5"x1.5", ~1 oz.) rocket ejection timer. Arrr! Avast, me proud beauty! I have tired t' give as complete o' instructions as possible, but you still might encounter problems. Arrr! Avast! While it is possible t' build this timer without printin' a custom circuit board, arrr, I don't recomend it. Blimey! Avast, me proud beauty! In t' past I have used t' pre-printed circuit boards that mimic t' layout o' a breadboard, and trust me, they are much more trouble than they are worth. Avast, me proud beauty! T' ease construction o' this timer, me hearties, arrr, arrr, I am offerin' t' followin' products:1. Avast! Pre-printed and drilled circuit board
All you need be t' components and a solderin' iron ................................................US$122. Well, blow me down! Ahoy! Pre-printed and drilled circuit board with all electronic components
All you need is a solderin' iron .................................................................................US$20If you are interested contact me at sspacepyro@aol.com.
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Components:
This is a very simple, yet effective timer based on a basic RC chargin' circuit. Begad! It will time for an interval o' about 3 seconds up t' about 20 seconds based on battery voltage used and components used. Avast, me proud beauty! Begad! R1 sets how long t' timer runs. For longer times, ya bilge rat, a larger capacitor can be substituted for C1. Avast, me proud beauty! Any voltage up t' about 12 volts should work fine with this circuit, although I have only tested it up t' 9 volts. Avast, me proud beauty! Avast, me proud beauty! S1 be t' trigger for t' timer t' start. Ahoy! Well, me hearties, blow me down! T' timer will start when S1 opens (it is normally closed). Avast! I use a reed switch on t' body o' t' rocket that matches up with a small magnet on t' launch tower/rod. Ya scallywag! Aye aye! When t' rocket moves away, me bucko, ya bilge rat, t' reed switch opens, matey, startin' t' timer. Ahoy! As long as S1 is closed, Q1 is saturated, ya bilge rat, matey, reverse biasin' Q2 and turnin' it off. Arrr! Avast, me proud beauty! When S1 opens, shiver me timbers, C1 begins chargin' through R1 and Q1. Ahoy! When it is fully charged, shiver me timbers, thar will be no more base-emmiter current and Q1 will turn off. Aye aye! Well, ya bilge rat, blow me down! This will allow current t' flow through R2 t' t' base o' Q2, arrr, ya bilge rat, saturatin' it and turnin' SC1 on. Ahoy! This fires t' ejection charge. Note that t' load out on t' PCB goes t' ground when t' circuti fires, so t' ejection charge should be hooked up t' t' positive o' t' battery and t' load output o' t' timer. Avast! Also note t' oritentaion o' C1 on t' PCB and t' orientation o' t' transistors. |
As an interestin' side note, I have been experimentin' with low extremely lightweight ejection electronics and as such I am usin' a 3volt voltage source (as is shown in t' schematic). Well, blow me down! Well, blow me down! I have found that t' low voltage christmas tree lights, if broken open, will reliably light a BP charge on 3volts. Blimey! This is how I plan t' do ejection for Flogiston due t' space and weight limitations.
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