Some friends would like to build a down-sized model of a two-stage sounding
rocket. I'm trying to come up with a design for a timer to ignite the
second stage. The timer should be triggered by a "g" switch which marks
first stage ignition, and time out after (an adjustable) 1.5-2 seconds,
just after the first stage burns out. Commercial designs are available for
around $90. I only need to build ONE of these andd don't have the
programmer so a pic or BASIC STAMP are out. Any ideas or schematics for an
analog or simple digital timer for this application?

On Tue, 29 Apr 2008 08:20:12 GMT, Smaug Ichorfang <sm@ug.the.orc
wrote:
Thanks! I'll give this consideration!

Some friends would like to build a down-sized model of a two-stage
sounding rocket. I'm trying to come up with a design for a timer to
ignite the second stage. The timer should be triggered by a "g"
switch which marks first stage ignition, and time out after (an
adjustable) 1.5-2 seconds, just after the first stage burns out.
Commercial designs are available for around $90. I only need to build
ONE of these andd don't have the programmer so a pic or BASIC STAMP
are out. Any ideas or schematics for an analog or simple digital
timer for this application?

---
View in Courier:


Vcc>-+---------+-----+---+------+--------+
| | | | 8| |
[10K] [10K] [1M]<-+ +---+---+ [100K]
| | Rt| 2|_ Vcc _|4 |
+-[100nF]-+-----|-----O|T R|O---+
| | 6| | |
+ +------|TH 7555| [100nF]
| | 7|_ |3 |
| O +-----O|D OUT|O---|--->OUT
| O +| | GND | |
| [3.3µF] +---+---+ |
| Ct| 1| |
GND>-+---------------+----------+--------+


T = 1.4 Rt Ct

JF

Some friends would like to build a down-sized model of a two-stage sounding
rocket. I'm trying to come up with a design for a timer to ignite the
second stage. The timer should be triggered by a "g" switch which marks
first stage ignition, and time out after (an adjustable) 1.5-2 seconds,
just after the first stage burns out.

On Tue, 29 Apr 2008 08:20:12 GMT, Smaug Ichorfang <sm@ug.the.orc
wrote:


Some friends would like to build a down-sized model of a two-stage sounding
rocket. I'm trying to come up with a design for a timer to ignite the
second stage. The timer should be triggered by a "g" switch which marks
first stage ignition, and time out after (an adjustable) 1.5-2 seconds,
just after the first stage burns out. Commercial designs are available for
around $90. I only need to build ONE of these andd don't have the
programmer so a pic or BASIC STAMP are out. Any ideas or schematics for an
analog or simple digital timer for this application?


---
View in Courier:


Vcc>-+---------+-----+---+------+--------+
| | | | 8| |
[10K] [10K] [1M]<-+ +---+---+ [100K]
| | Rt| 2|_ Vcc _|4 |
+-[100nF]-+-----|-----O|T R|O---+
| | 6| | |
+ +------|TH 7555| [100nF]
| | 7|_ |3 |
| O +-----O|D OUT|O---|--->OUT
| O +| | GND | |
| [3.3µF] +---+---+ |
| Ct| 1| |
GND>-+---------------+----------+--------+


T = 1.4 Rt Ct

JF

Some friends would like to build a down-sized model of a two-stage sounding
rocket. I'm trying to come up with a design for a timer to ignite the
second stage. The timer should be triggered by a "g" switch which marks
first stage ignition, and time out after (an adjustable) 1.5-2 seconds,
just after the first stage burns out. Commercial designs are available for
around $90. I only need to build ONE of these andd don't have the
programmer so a pic or BASIC STAMP are out. Any ideas or schematics for an
analog or simple digital timer for this application?

Some friends would like to build a down-sized model of a two-stage sounding
rocket. I'm trying to come up with a design for a timer to ignite the
second stage. The timer should be triggered by a "g" switch which marks
first stage ignition, and time out after (an adjustable) 1.5-2 seconds,
just after the first stage burns out. Commercial designs are available for
around $90. I only need to build ONE of these andd don't have the
programmer so a pic or BASIC STAMP are out. Any ideas or schematics for an
analog or simple digital timer for this application?

John Fields wrote:
On Tue, 29 Apr 2008 08:20:12 GMT, Smaug Ichorfang <sm@ug.the.orc
wrote:


Some friends would like to build a down-sized model of a two-stage sounding
rocket. I'm trying to come up with a design for a timer to ignite the
second stage. The timer should be triggered by a "g" switch which marks
first stage ignition, and time out after (an adjustable) 1.5-2 seconds,
just after the first stage burns out. Commercial designs are available for
around $90. I only need to build ONE of these andd don't have the
programmer so a pic or BASIC STAMP are out. Any ideas or schematics for an
analog or simple digital timer for this application?


---
View in Courier:


Vcc>-+---------+-----+---+------+--------+
| | | | 8| |
[10K] [10K] [1M]<-+ +---+---+ [100K]
| | Rt| 2|_ Vcc _|4 |
+-[100nF]-+-----|-----O|T R|O---+
| | 6| | |
+ +------|TH 7555| [100nF]
| | 7|_ |3 |
| O +-----O|D OUT|O---|--->OUT
| O +| | GND | |
| [3.3µF] +---+---+ |
| Ct| 1| |
GND>-+---------------+----------+--------+


T = 1.4 Rt Ct

JF

Looks like that's going to fire the second stage at liftoff or
immediately when g-switch drops out depending whether is it NO or NC.
That circuit produces a pulsewidth of 1.4RC.

On Tue, 29 Apr 2008 08:20:12 +0000, Smaug Ichorfang wrote:

Some friends would like to build a down-sized model of a two-stage sounding
rocket. I'm trying to come up with a design for a timer to ignite the
second stage. The timer should be triggered by a "g" switch which marks
first stage ignition, and time out after (an adjustable) 1.5-2 seconds,
just after the first stage burns out. Commercial designs are available for
around $90. I only need to build ONE of these andd don't have the
programmer so a pic or BASIC STAMP are out. Any ideas or schematics for an
analog or simple digital timer for this application?

When I was a kid, Estes rocket motors were available with an "after-charge",
which is basically a hole at the top of the motor that shoots hot gas
into the nozzle of the second stage right at burn-out. So, no electronics,
batteries, squibs, none of that schtuff was needed.

The idea of a 1.5-2 second timer with batteries and squib and all of that
just seems ludicrous on a rocket where the first stage only lasts 1.5-2
seconds.

Good Luck!
Rich

On Tue, 29 Apr 2008 08:20:12 +0000, Smaug Ichorfang wrote:

Some friends would like to build a down-sized model of a two-stage
sounding rocket. I'm trying to come up with a design for a timer to
ignite the second stage. The timer should be triggered by a "g"
switch which marks first stage ignition, and time out after (an
adjustable) 1.5-2 seconds, just after the first stage burns out.
Commercial designs are available for around $90. I only need to
build ONE of these andd don't have the programmer so a pic or BASIC
STAMP are out. Any ideas or schematics for an analog or simple
digital timer for this application?

When I was a kid, Estes rocket motors were available with an
"after-charge", which is basically a hole at the top of the motor
that shoots hot gas into the nozzle of the second stage right at
burn-out. So, no electronics, batteries, squibs, none of that schtuff
was needed.

The idea of a 1.5-2 second timer with batteries and squib and all of
that just seems ludicrous on a rocket where the first stage only lasts
1.5-2 seconds.

And you are no longer a kid. Black powder motors Estes sells are no longer

On Tue, 29 Apr 2008 22:19:56 GMT, Rich Grise <rich@example.net> wrote:

On Tue, 29 Apr 2008 08:20:12 +0000, Smaug Ichorfang wrote:

Some friends would like to build a down-sized model of a two-stage
sounding rocket. I'm trying to come up with a design for a timer to
ignite the second stage. The timer should be triggered by a "g"
switch which marks first stage ignition, and time out after (an
adjustable) 1.5-2 seconds, just after the first stage burns out.
Commercial designs are available for around $90. I only need to
build ONE of these andd don't have the programmer so a pic or BASIC
STAMP are out. Any ideas or schematics for an analog or simple
digital timer for this application?

When I was a kid, Estes rocket motors were available with an
"after-charge", which is basically a hole at the top of the motor
that shoots hot gas into the nozzle of the second stage right at
burn-out. So, no electronics, batteries, squibs, none of that schtuff
was needed.

The idea of a 1.5-2 second timer with batteries and squib and all of
that just seems ludicrous on a rocket where the first stage only lasts
1.5-2 seconds.

Good Luck!
Rich


Long ago I made a 3 stage rocket with those types of motors.
Never found the rocket afterward.
There was a note inside..'If found please call......'
Never got a call

And that was the last of my rocketery...
Electronics looked better as a hobby.
Breadboards don't take off and disappear. :P


D from BC
British Columbia
Canada

Breadboards don't take off and disappear.

On Tue, 29 Apr 2008 19:01:44 -0700, D from BC
myrealaddress@comic.com> wrote:


Breadboards don't take off and disappear. :P

---
Some of mine have. ;)

JF

John Fields <jfields@austininstruments.com> wrote in
news:hsqg145utfqpbp32h6jgdj481kshde9kft@4ax.com:

On Tue, 29 Apr 2008 19:01:44 -0700, D from BC
myrealaddress@comic.com> wrote:


Breadboards don't take off and disappear. :P

---
Some of mine have. ;)

JF

I think God really likes some of my rockets; He's kept enough of them.
Either that or they just got "stuck".