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