Tony Van Roon Model Rocket Delay Controller

[brockrwood]

Mr, Van Roon passed away in 2011. Luckily his electronic circuits website lives on.

I have had the parts for his model rocket delay controller for many years now but have never gotten around to building it.

I am now hankering to get this built.

If anyone has already built it, tips are appreciated.

https://www.learningelectronics.net/VA3AVR/gadgets/rocket.html

 

[Cape Byron]

Interesting project.

I wonder if you could use it to drive a large display board giving a visual countdown for spectators?Always been a thought of mine as an attention getter at public launches.

 

[tsmith1315]

Always been a thought of mine as an attention getter at public launches.

Same here!

 

[shockie]

You could use either an arduino or an esp32 to display the countdown on a display screen and you can do it wirelessly, ie, the display could be anywhere on the range

 

[brockrwood]

You could use either an arduino or an esp32 to display the countdown on a display screen and you can do it wirelessly, ie, the display could be anywhere on the range

If I could hook up this extremely old school, analog electronics circuit filled with 555 timers, a darlington transistor, and even a 6 volt lamp, up to an Arduino, it would be way cool. Old school meets new school!

The Arduino would have to somehow count the pulses coming out of a 555 or feeding the piezo buzzer. Would be hard to use this circuit for a precise countdown display.

You could just use an Arduino to control the countdown, a display of the countdown, and when the count is finished, send a control signal to the TIP 120 to turn on the current to the igniter for 3 seconds. The Arduino would replace most of this circuit except for the high current, output transistor switch.

 

[brockrwood]

Interesting project.

I wonder if you could use it to drive a large display board giving a visual countdown for spectators?Always been a thought of mine as an attention getter at public launches.

I just looked at the circuit again. They delay timer is contolled by one of 6 different Resistor/capacitor combinations. They keep the output of first 555 timer high for an approximate amount of time. When the R/C combo fully discharges, the output of the first 555 goes low. That makes the output of the 555 controlling the base of the darlington transistor go high for 3 seconds. The current to fire the igniter goes througb the darlington.

The problem with using this to drive a display is that the R/C timing circuits are not precise. The time they take to discharge varies with temperature and other factors. It would be hard to get a consistent countdown display using this very old school circuit. Some sort of microcontoller or at least a crystal controlled oscillator would be better for that.

 

[brockrwood]

Interesting project.

I wonder if you could use it to drive a large display board giving a visual countdown for spectators?Always been a thought of mine as an attention getter at public launches.

Another favorite on-line circuit blogger, Swagatam, has a circuit to do a 7 segment display countdown timer using discrete logic chips, if you are resisting (like I am) doing everything with a microcontroller.

https://www.homemade-circuits.com/simple-digital-timer-circuit-with-2-digit-display/

 

[brockrwood]

Another favorite on-line circuit blogger, Swagatam, has a circuit to do a 7 segment display countdown timer using discrete logic chips, if you are resisting (like I am) doing everything with a microcontroller.

https://www.homemade-circuits.com/simple-digital-timer-circuit-with-2-digit-display/

Shoot. That was a count UP timer not a count DOWN timer.

Yep. It is easier to do this stuff with an Arduino.