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