# Smallest, Most Simple Apogee Fire Electronics

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##### I don't do spirals
TRF Supporter
What is the absolutely, positively MOST SIMPLE electronics out there that will simply fire a charge at apogee. Second event fine, just don't need all the bells & whistles - It hits apogee, BP charge goes off. The ultimate would be a simple board that fires both a timed charge (2.5 seconds after liftoff detected) and at apogee

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#### mbeels

##### Yes balsa
TRF Supporter
The Eggtimer Quark is pretty simple, it doesn't require a computer for programming, just set the jumpers.

#### n27sb

##### N27SB
TRF Supporter
The Eggtimer Quark is pretty simple, it doesn't require a computer for programming, just set the jumpers.
I Agree. The Quark is hard to beat

#### prfesser

Someone out there might have a Magnetic Apogee Detector kit from years gone by. It would fit into a BT-5. Only fired apogee, no dual deploy.

#### Dipstick

##### Well-Known Member
TRF Supporter
The old Featherweight Parrot was the best for this. It had an onboard battery. Egg timer Quark would also be my suggestion, and for simple apogee event a small light battery can be used. I think you would need a resistor to get away with using only apogee event.

#### n27sb

##### N27SB
TRF Supporter
The old Featherweight Parrot was the best for this. It had an onboard battery. Egg timer Quark would also be my suggestion, and for simple apogee event a small light battery can be used. I think you would need a resistor to get away with using only apogee event.
This is from the Quark user guide in regard to single channel use:

(Sidebar discussion....)
OK, you may be wondering how to intentionally disable a channel, for example if you only want to use the Quark for single-parachute deployment in lieu of motor ejection. The Quark requires some kind of load on the deployment channels to pass the continuity checks, but it’s really not very picky about what that load might be. We typically use 100 ohm 1/4W resistors in place of an igniter to disable a channel, they draw very little current but the resistance value is low enough so that it’s below the deployment checking circuitry’s voltage threshold.
(End of Sidebar...)

- 11 -

The Featherweight Raven is the same size as the Quark, and its default settings will fire its "Apo" channel at apogee, without changing anything. It uses a very small battery and you can ignore all of its other capabilities if you want to. And if you want to add another deployment 2.5 seconds after liftoff, you can do that too, using the Featherweight Interface Program to set the desired time.

#### Cameron Anderson

##### Well-Known Member
What's the intent behind the liftoff 2.5 second event?

#### cwbullet

##### Obsessed with Rocketry
Staff member
Global Mod
What's the intent behind the liftoff 2.5 second event?
Timed deployment and staging.

##### I don't do spirals
TRF Supporter
Timed deployment and staging.
38mm Main Body tube, 3 fins, 3 boosters. Three boosters on launch, sustainer ignite after 2.5 seconds

#### Cameron Anderson

##### Well-Known Member
38mm Main Body tube, 3 fins, 3 boosters. Three boosters on launch, sustainer ignite after 2.5 seconds
Raven4.
4 channels, easy to program, small, reasonably priced, and has good staging options.
I own 2 and fly lots of two-stage stuff with them.

38mm Main Body tube, 3 fins, 3 boosters. Three boosters on launch, sustainer ignite after 2.5 seconds
Yikes! Staging separation charges on a timer is one thing. But timer-based airstarts is not a safe practice, and has caused several serious injuries. Once a timer's liftoff is detected, then your airstart is like a ticking time bomb that could go off on the ground, or while the rocket is pointed back at the flight line after a CATO or airframe failure, at any altitude. IMO, no airstarts should happen without at least an altitude check, and preferably an altitude/time check to make sure that it has a nominal-enough boost to get it above a predicted altitude before a time limit. There are also more sophisticated gyro-based flight angle checkers that you can use that will prevent ignition after almost any type of off-nominal boosts, but at least a simple altitude check will cover most of the worst failure cases.

Thanks, I wasn’t aware of that product. Glad it’s out there.

#### Cameron Anderson

##### Well-Known Member
Spend twice the money of an apogee timer and get 4 times the product in a Raven 4 (not a paid endorsement, but since Adrian can't push his product without sounding like a shameless plug I will advocate for him - solid flight computer with great customer service).

Something the same price of an apogee timer is the Altus Metrum EasyTimer. It has tilt lockouts for staging but not an apogee detect in the traditional sense (I bought an Easytimer but I haven't flown it yet so I'm not sure of its total capabilities).

#### cerving

##### Owner, Eggtimer Rocketry
TRF Supporter
The Eggtimer Proton will do both of those things, and can fit in a 38mm coupler. If you really are only looking for the apogee event, we have a product coming out in a few weeks that will take care of that.

#### ksaves2

Someone out there might have a Magnetic Apogee Detector kit from years gone by. It would fit into a BT-5. Only fired apogee, no dual deploy.
Yup,
I have a couple of Robert Galejs MAD units from a few years ago. Work very nicely but one has to be absolutely careful to make sure they don't turn them on until upright on the pad. If there is an igniter failure, one has to turn it off and let it sit for awhile to make sure that charge doesn't fire when tipping the rocket over. If one just lifts up the rocket on the rail to replace the motor starter, no problem. http://www.aeroconsystems.com/electronics/mad.htm I don't think the kits are available anymore. I dorked one and got a hold of Professor Galejs and he fixed it for me! That was a long time ago and I did put a twenty dollar bill in the box of the dorked unit and it still works. I think I have 3 or 4 of them lying around. I like to build kits.

I have a couple of Zeptomag units and they work very nicely. Looks like they are still available if one doesn't mind ordering from overseas. I've flown one and it's a bit easier and safer than the old Galejs units: https://www.tindie.com/products/ZeptoBit/zeptomag/

Combine it with a Jolly Logic Chute release and viola', old school one point dual deploy. One point in that one only needs to do one BP charge for apogee with the MAD unit and done. Use the JLCR for main deployment. Like I've said, the ASP large WAC Corporal with the 39mm motor hole is designed (inadvertently) for this type of setup. Just use screws to put the coupler on the NC and there's a nice bay for the MAD unit in there. Use some good epoxy fillets on the coupler to the bulkhead and good to go. I flew two of them that way and have two more WACs to build I like'em so much.

Kurt Savegnago

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#### ksaves2

The old Featherweight Parrot was the best for this. It had an onboard battery. Egg timer Quark would also be my suggestion, and for simple apogee event a small light battery can be used. I think you would need a resistor to get away with using only apogee event.
The very bad thing about the Parrot was the continuity detection was defective period. If one was using both channels for deployment (Apogee and Main) the continuity indication was the same with either or both channels. That means if one was depending on both channels for apogee and main deployment, if one had continuity and the other didn't, the notification was the same. I had an apogee failure in the past due to a continuity issue that I couldn't discern on the pad.
That is one of the reasons it went out of production and you got the Raven.

Most deployment altimeters give a discerning beeping sound to indicate continuity of BOTH channels! The Parrot only did the same beep whether one or both had continuity. That means if one ematch had no continuity, the continuity beep was the same! Hence one would have an "off-nominal" flight.

O.k. So use an ematch tester to check each bare ematch before each flight with a Parrot and one should be in a good situation.

Kurt Savegnago

#### pbahorich

##### Active Member
It's hard to beat Eggtimer if you are willing to solder the parts on.