Wiring diagram for L3 with Eggtimer

[chuck5395]

I'm currently working on my L3 project and I'm up to doing the layout for my electronics bay. I've been flying a pair of Eggtimer altimeters for a couple of seasons now and I'd like to use a pair in my L3. I'm looking for someone who has used Eggtimers in their L3 project to please share their wire schematic.

Thanks
-Chuck

 

[cerving]

Here's how I wired the two Quantums in my L3.

 

[OverTheTop]

FWIW I would use a second battery just for the pyro on at least one of the alts. People have had batteries go off-line when a pyro fires, so if there is only one then the altimeter is off too.

Personally I use a battery for the altimeter and a battery for each pyro mostly, and switch both batteries with the pullpin. Here is a contemporary example:


Further details here: https://forum.ausrocketry.com/viewtopic.php?f=6&t=5019&start=84
Switching both batteries has the advantage I can prep a rocket before traveling to the launch, and if the launch is a scrub it can stay packed and undisturbed until the next available flight date.

Forgot to mention that I am looking at using some 10mAh 1S Lipo cells for the pyros, instead of my usual 120mAh 2S LiPos. They are tiny, about 1/2" square. I still need to test to ensure they are capable of a decent current delivery. I don't expect to be disappointed.

[edit: Fixed link to be more direct]

 

[rharshberger]

Simple but functional works with Eggies and others, for alts with switch terminal I just jumper them and place a screw switch in the appropriate battery lead. The attached drawing was for my 5.38" Cherokee-D L3 Cert rocket. Determining the proper leg of the battery lead was as easy as emailing Jim Amos (MW) and Cris Erving (Eggtimer).

 

[OverTheTop]

Determining the proper leg of the battery lead was as easy as emailing Jim Amos (MW) and Cris Erving (Eggtimer)

With fully independent altimeter circuits it actually doesn't matter which lead of the battery the switch is in. Convention says we normally switch the positive.

It does become important if the altimeters are fed to other circuits (like in my circuit above) in which case the grounds are nearly always connected together and the positives switched. Note that in my earlier schematic the grounds are connected as I feed the battery voltages back to the TeleMega in the nosecone for live reporting of the battery state and also for ignition of the sustainer motor. So as far as what the OP was asking for in this thread just look at the positive connections from the batteries to the alts and eMatches. Ground returns in your situation do not need to be connected together.

 

[ksaves2]

K.I.S.S. it. Cris' diagram is the winner though Rich's is a variation is "extra sure". Just be absolutely certain the battery connections are sure and secure. The large batteries in the quantums can well handle the requirements.
If doing a NAR cert, switch on the battery leg to please the safety mavens. In reality, there is a trace that doglegs over from the battery terminal to the switchblock and it's moot whether or not the switch is on the battery line or
on the switchblock.

 

[chuck5395]

Here's how I wired the two Quantums in my L3.

View attachment 362160

Cris,
Does the fact that the Quantum is WiFi enabled change the way you set it up? The Eggtimer doesn't have that feature. If you were to use the Eggtimers instead, would you add another switch (or two) to put it in safe mode?
-Chuck

 

[anbhtblr]

I agree that KISS should be the guiding principal. While I didn't use Eggtimer, although I do own some, the level of documentation needed transfers to almost any equipment. Attached is an excerpt from my L3 doc.

 

[chuck5395]

Thanks Rich,
I guess the question for me is in regards to how you (and others including the other Rich in this thread) short the switch terminals to the on state and then put the actual switch in line with the battery. I'm beginning to think that this is the preferred (and safer) configuration regardless of altimeter manufacturer?

 

[rharshberger]

I just make a short wire jumper to go between the two switch positions on the teminal block.
In this picture the jumper is actually a section of resistor lead left over from building a Eggfinder product.

 

[anbhtblr]

Shorting the on-board switch circuit to the on state is a simple jumper wire across the terminals. For the battery switch I solder a switch between the battery's positive terminal and the positive battery terminal on the board. The switch is mounted such that a pull pin closes the switch when removed (hopefully when the rocket is on the rail). This does mean that the board has to go through it startup/diagnostics with the rocket on the rail. I only use this for cert flights, and normally I use the on-board switch terminals. Hope this helps.