The Eggtimer - A full-function multiple-deployment flight computer for only $40

[matthew]

Yeah I saw that. No dimensions shown- are they specified elsewhere?

Hi Al. There's been some discussion about hole spacing right here in the thread.

 

[H_Rocket]

Actually I'm looking for mechanical dimensions and the mounting hole positions.

 

[awseiger]

Actually I'm looking for mechanical dimensions and the mounting hole positions.

Would a PCB footprint help? I'm working on an AV bay sled that accepts various altimeters using headers, and then screwing them down. I could start with the egg-timer, if you wish.

It won't happen overnight, though.... College is a wonderfully time-consuming prospect....

 

[H_Rocket]

Yeah, that's basically what I want. I have a generic sled and have spacer plates I use to adapt different altimeters. I just want the outside dimensions and the center to center dimensions for the mounting holes (with references to the edges of course).

 

[Onebadhawk]

Is this what your looking for Al.............

https://www.eggtimerrocketry.com/attachments/File/Eggtimer_RevC_Mounting_Template.pdf


Teddy

 

[H_Rocket]

People keep pointing to that one. When I open it there is an image of the board, however no numerical dimensions. Are the rest of you seeing something else?

 

[thobin]

Print it and whip out a ruler I think it is to scale.


TA

 

[Onebadhawk]

Nope,,,,, that's it,,,,, sorry Al,,,,,
I didn't realize you were made aware of that one........

Teddy

email customer support,,,,,,,
Cris Erving will tell you dimensions..........

 

[cerving]

Ah, I see what you're looking for now...

I'll get the dimensions posted. The template IS to scale, but it's pretty tiny so actual dimensions would be handy.

People keep pointing to that one. When I open it there is an image of the board, however no numerical dimensions. Are the rest of you seeing something else?

 

[conman13]

Unfortunately I had to break off the 820ohm resistors. Can I replace these with 820ohm 3W resistors?

 

[cerving]

Yes, but they probably wouldn't fit. I'll send you some.

Unfortunately I had to break off the 820ohm resistors. Can I replace these with 820ohm 3W resistors?

 

[conman13]

Ok thanks let me know if you need any money for shipping.

 

[cerving]

Nah, I could probably ship 100 of them with one stamp...

 

[XJChris]

I just want to confirm my thought on this... I'm using a 7.2V LiPo that should be able to run the logic as well as fire the igniters for dual deploy. Will I need to connect the leads to all three battery connection points (B+/-, BattA+/-, and BattB+/-)?

By the way, I really enjoyed putting this together. It was a wonderful sound when I plugged it in for the first test and heard the beeps; confirming that I didn't mess it up too bad.

 

[troj]

Got my Eggtimers today; thanks, Chris!

-Kevin

 

[cerving]

I assume you mean a 2S/7.4V LiPo. Yes, you would connect all three "+" leads together to the "+" (red) lead of your battery, and all three "-" leads to the "-" (black) lead of your battery. I would recommend two switches: One on the "+" side to the Eggtimer power, and a second one on the "+" side to the deployment channels' power. At the pad, you turn on the Eggtimer power, and when it starts to beep (before it does the self-test) you turn on the deployment power. Wait about 30 seconds until you get the "Ready" chirp/light, and you're good to go.

One thing that you do need to consider if you are using a single battery is the current draw of your igniters, and the current capacity (C rating) of your battery. If you're flying Q2G2s for your deployment, just about any LiPo pack that you are likely to find is going to be fine. If you are doing an airstart and have some kind of high current igniter (anything other than a dipped ematch), I would strongly recommend using a separate deployment battery.

I just want to confirm my thought on this... I'm using a 7.2V LiPo that should be able to run the logic as well as fire the igniters for dual deploy. Will I need to connect the leads to all three battery connection points (B+/-, BattA+/-, and BattB+/-)?

By the way, I really enjoyed putting this together. It was a wonderful sound when I plugged it in for the first test and heard the beeps; confirming that I didn't mess it up too bad.

 

[XJChris]

I assume you mean a 2S/7.4V LiPo. Yes, you would connect all three "+" leads together to the "+" (red) lead of your battery, and all three "-" leads to the "-" (black) lead of your battery. I would recommend two switches: One on the "+" side to the Eggtimer power, and a second one on the "+" side to the deployment channels' power. At the pad, you turn on the Eggtimer power, and when it starts to beep (before it does the self-test) you turn on the deployment power. Wait about 30 seconds until you get the "Ready" chirp/light, and you're good to go.

One thing that you do need to consider if you are using a single battery is the current draw of your igniters, and the current capacity (C rating) of your battery. If you're flying Q2G2s for your deployment, just about any LiPo pack that you are likely to find is going to be fine. If you are doing an airstart and have some kind of high current igniter (anything other than a dipped ematch), I would strongly recommend using a separate deployment battery.

Thanks Chris, that's exactly what I was thinking; just needed a sanity check. I am planning on using Q2G2s so the current should be relatively small.

 

[dixontj93060]

Thanks Chris, that's exactly what I was thinking; just needed a sanity check. I am planning on using Q2G2s so the current should be relatively small.

+1 on this. Thanks for the explanation.

 

[conman13]

I know it's already been asked but I can't find it. So what size are the mounting holes on the rev c board?

 

[cerving]

They're #4, spaced .0825" x 3.725" (about 21mm x 95mm). The spacing is the same for both RevC and RevD boards.

 

[conman13]

They're #4, spaced .0825" x 3.725" (about 21mm x 95mm). The spacing is the same for both RevC and RevD boards.

Ok thanks. what size screws did you use to mount it?

 

[troj]

First EggTimer assembled. Egads, those are tiny pads which are hard on those of us who now need reading glasses....

I still need to test it out; will do that later.

-Kevin

 

[cerving]

Ok thanks. what size screws did you use to mount it?

It depends on your sled. I've simply used double-stick foam tape for minimum-diameter (BT55) MPR projects, just build it up until it's thick enough. It ain't gonna come loose, trust me (assuming you get 3M tape and not the cruddy generic stuff). For larger projects, I'll make a sled of basswood or plywood, epoxy some 1/4" square stringers to mount the Eggtimer, and use #4 x 3/8" self-tapping screws. For really large projects, i.e. L2-size, I'll use #4 machine screws, typically 1/2" long, with Nylock nuts.

 

[cerving]

I'm nearsighted, which may be a blessing in disguise in this case. I have to take OFF my glasses to do close work.

Lighted magnifiers are a good thing...

First EggTimer assembled. Egads, those are tiny pads which are hard on those of us who now need reading glasses....

I still need to test it out; will do that later.

-Kevin

 

[T-Rex]

Even an unlighted magnifier helped a lot when I assembled my second one.

 

[dixontj93060]

Even an unlighted magnifier helped a lot when I assembled my second one.

Big fluorescent ring magnifier for me.

 

[conman13]

As I was soldering on the battery connectors one of the metal disks cam off. As I plugged the battery in it did not turn on. Is it because of the small little disk or because of something else?

 

[awseiger]

As I was soldering on the battery connectors one of the metal disks cam off. As I plugged the battery in it did not turn on. Is it because of the small little disk or because of something else?

Sounds like you lifted a trace.... Try soldering it in from the other side.

As with all complex electronic projects, it could be ANYTHING. But I'd put my money on that.

 

[cerving]

Check the two RST pads with a digital voltmeter, you should see 3.3V across them (or whatever you battery voltage is, if you're not using the regulator). If it's zero, then you have lifted a pad and lost continuity. Email me a closeup of the board ([email protected]), and if that's the case I'll give you a workaround.

 

[conman13]

One more question going out to anybody. I got the board all soldered up and did a master reset. I was going to test the deployment channels and plugged in a lightbulb on both channels and pressed enter on my PC. However no continuity came up for either channel so I tested it and the bulb did not light. Both the channels are set to an igniter and have been saved. Us there something I'm doing wrong? I also checked the voltage in the deployment channel and it came up as 8v. There was also no voltage on the continuity bulbs. If no one has any ideas I may just get another and go from there. Thanks.