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Optical apogee sensor circuit (not reinventing just knackling)

Posted: Sat Sep 03, 2016 11:24 am
by fenrisulfr
Hi

Already tried splicing bottles, total failure, so while I rethink that I'm doing this. I've played around with analogue electronics on and off for years. Make my own PCB's using the toner transfer method. I have played with the arduino but ran into a problem with programming......... Basically I can't (I have read copious books on the subject done all the examples and I cannot do free form programming (Look on it as a sort of dyslexia)) So I stick with analogue. Yes it means more chips and support components but at least I can make it work.

Any way my 'tweak' to the optical apogee circuit. First up this is based on the prior works of MB rockets and Flori and Bibblycheese. Hope I got all that right.

All I have done is just added things rearranged bits and put a circuit together. Currently only simulated but theoretically it will do the job.

So first 2 IC's are actually 2 halfs of a 556 as per MBs circuit. A launch detect with a time delay on the NC switch going open at launch. I have wired this into another half of a 556 which acts as a set/reset switch. This in turn controls power to the light/dark comparator chip combo. This then goes onto a full set of MBs circuit but switched by a transistor.

To sum up. At power up the circuit starts in safe mode, the optics wont react to a careless hand over the light sensing end. Once launched there is a delay before the optics go live. At apogee detection there is a delay before shute release. Both delays can be set using the relevant trimpot. Basically nothing special just messing about as I have lots of bits to play with and too much time on my hands. Here's a pic to go with it. Additionally there is a power on delay on the reset pin of the 555/556 IC's that helps prevent any 'random' behaviour at power on.
rocket_chute_releaseB.jpg

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Wed Sep 07, 2016 5:10 pm
by Blenderite
Have you tried the ServoChron(tm)2 system by U.S. Water Rockets? It is really easy and simple to set up. MI imagine that would be a good bit cheaper than buying all those parts for the design you have created, assuming you don't already have the parts laying around.

Here is the forum thread with more information: http://www.wra2.org/forum/viewtopic.php?f=5&t=1599

You can purchase the MSP430 board direct from Texas Instruments: https://store.ti.com/MSP-EXP430G2.aspx (TI was $6.99 to ship to my house)
Or you can purchase them from Mouser: http://www.mouser.com/ProductDetail/Tex ... 252b5KGk2B (Mouser is $7.99 to ship to my house)

Another option that USWR has created is the Launchpad ALTimeter. This enables you to combine your parachute release system with an altimeter. It uses the same TI Launchpad board along with a simple Pressure sensor breakout board and a little speaker. It works well (I have not flown it, but I have bench tested it quite a bit with great success, not a single failure after 30+ simulated launches). This one takes a little more skill to assemble, but based on your original post, I doubt it would be difficult for you at all. Check out USWR's website for more details: http://www.uswaterrockets.com/documents ... manual.htm

If you would rather go with your system, I would love to hear how well it works! I definitely have not seen a optical system that is that well designed.

-Blenderite

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Fri Sep 09, 2016 5:44 pm
by fenrisulfr
Hi there

Now that is interesting. Cheap as well. Also the programming is done and is free! So a bit of a rethink going on :undecided:

I do have all the parts (for the analogue) just as a matter of having collected bits and bobs over the years. I have drawn up the PCB(s) and although feasible
weight becomes an issue even though I managed to crunch the component spacing down to minimise overall size it still comes out bigish.

Extra weight robs height sooooooooo. Why not draw up a bare bones PCB for the 430G2? Use the Launchpad to program the chip transfer
chip to the BBPCB and done. I think there is an IDE enviroment that can be used with Linux to program the uC? I am a Linux user but can
access windows if I'm sedated, blindfolded, and lastly threatened with the ginger beer trick :stars:

Here's a a quick draw up of a BBPCB based on my current understanding of the IO requirements from the Datasheets and the USWR
resources. The Yellow outline is the sensor package used for altitude sensing. Servo header on the right; +ve / -ve are jumpered
as , unless things have changed since I last did R/C stuff, some manufacturers wired their supply lines opposite hand to others.
So this is covered by soldering jumpers in according to need.

Also based it on a 20 pin IC as it seems what is supplied to order may vary? (From what I've read in passing)
Barebones430.jpg

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Fri Sep 09, 2016 6:28 pm
by fenrisulfr
Just stumbled across another thread where a chap has done a BB430. No Crystal with associated caps.. Is that right? If so I can save some more space :D

Re: Optical apogee sensor circuit DITCHED. For TI 430G2

Posted: Sat Sep 10, 2016 7:34 pm
by fenrisulfr
Well After more reading, etc, etc. I'm pretty sold on the USWR AiTImeter. Cheap hardware free software and I've refined a nice BB PCB for it. I just have to get the main parts and a few components to do it. Namely CR125 resistors and axial ceramic caps, for their small size, momentary contact switches, 20pin DIL socket and male and female headers. I have the 3mm LEDs, electrolytic cap and the kit to make the PCB.

The PCB is single sided. Components in yellow are fitted on the trace side of the PCB. I've taken some cues from Uberpixels BB build thread but I have stuck to some basic 'rules' if you will. Decoupling caps on the power lines and the resistor/caps on the switches as shown in the TI data sheet schematic rev1.5. Apart from providing a very brief pulse to pins 5 and 16, at power up, they also act to debounce the switches when they are operated. These parts are not on Uberpixels build and it works. I'm old school, and old, and was 'taught' heavily about smoothing power lines and debouncing switches to avoid possible issues.
Barebones430r1.jpg
BarebonesPCB430r1.jpg

Re: Optical apogee sensor circuit DITCHED. For TI 430G2

Posted: Sat Sep 10, 2016 9:42 pm
by Blenderite
fenrisulfr wrote:Well After more reading, etc, etc. I'm pretty sold on the USWR AiTImeter. Cheap hardware free software and I've refined a nice BB PCB for it. I just have to get the main parts and a few components to do it. Namely CR125 resistors and axial ceramic caps, for their small size, momentary contact switches, 20pin DIL socket and male and female headers. I have the 3mm LEDs, electrolytic cap and the kit to make the PCB.

The PCB is single sided. Components in yellow are fitted on the trace side of the PCB. I've taken some cues from Uberpixels BB build thread but I have stuck to some basic 'rules' if you will. Decoupling caps on the power lines and the resistor/caps on the switches as shown in the TI data sheet schematic rev1.5. Apart from providing a very brief pulse to pins 5 and 16, at power up, they also act to debounce the switches when they are operated. These parts are not on Uberpixels build and it works. I'm old school, and old, and was 'taught' heavily about smoothing power lines and debouncing switches to avoid possible issues.

Barebones430r1.jpg
BarebonesPCB430r1.jpg
That looks awesome! If that works, I will have to try that myself. I got the un-etched PCB's and fluid laying around from another project so that would be awesome! Keep us up to date!

Another thing you could do, once you got the ALTimeter system working, you could then develop your deployment system for those who want to go with that style of deployment. That way you know your rocket will be safe even if it fails!

Good Luck!!
-Blenderite

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Sun Sep 11, 2016 7:26 am
by fenrisulfr
Hi

Thanks for the enthusiasm. A bit more fiddling and messing later. Added some pads on the power rails that run under the uC that can be used to jump power to the pins of the sensor board in the event a 14 pin uC is fitted as per the USWR reference tutorials. Then I thought why not make a second version of the PCB to suit the 14 pin version anyway. So two versions now. The 20pin version can take both and you just wire in the power jumpers in the event you fit a 14 pin uC or make a 14 pin PCB for the 14 pin uC where all the wiring is and traces are sorted. The 14 pin PCB is .5mm narrower (wow) and 3mm shorter than the 20pin PCB (gosh).

Not much of a saving but hey I'm bored! I may revisit the analogue optical PCB design again once I've got and done this.
BB430G2xPCBs.jpg

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Mon Sep 12, 2016 4:47 am
by anoymous
Good thing you started using the uswr system, otherwise i would've linked you to this:
http://www.wra2.org/forum/viewtopic.php?f=5&t=2773
If you ever want to start using arduino again, in that topic is everything i got about it

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Tue Sep 13, 2016 2:28 pm
by Jamie5335
Hello fenrisulfr,

I just wanted to briefly say that I think its great to see others coming up with there own designs for a water rocket flight computers. There are plenty out there, but after all, its fun and rewarding to design, build and test your own. There hasn't been much on optical sensor trigger systems on the main stream water rocket social media platforms recently so its great to see that your trying something different. Good Luck with it and I hope it works! Its great to see a 555 timer in there!

I am surprised you find the coding more difficult than the analogue circuits. I am about to start my Electronic Engineering degree soon and I am looking forward to learning more about analogue. But as others have stipulated, you can do pretty much anything with an Arduino Nano purchased of eBay for very little money! Plus with coding, alot of what you write for these projects is repeated and I tend to reuse alot of code from existing projects, so only a small amount of the code will actually take a while to develop.

Jamie B

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Tue Sep 13, 2016 6:13 pm
by fenrisulfr
Hi there

Anoymous: your arduino sys looks great. how has it performed?

Jamie B: Yep programming....... I had trouble with basic (I am that old) I was able to do the individual routines as it were (in the basic) but pulling the various routines together to form a larger functional program is where things got problematic. Same with arduino sketch. I can read and understand a sketch or at least get the gist. but it all breaks down when I attempt to do it.

I think it's why I prefer messing with the hardware. Playing with electronics is fun up to a point. I have some blanks in my knowledge that I cannot resolve and sometimes a project will die because of it. But so far I''ve managed to have fun on and off for the most part. when the fun stops so do I :/

Re the optical apogee sensor. I will revisit it at a later date. I have some niggling worries about it. But I may be over thinking it. Purely on the detection itself with regards to how the rocket can spin as it goes up and the relationship of shadows cast across the sensors during this and other events. probably over thinking...

Here's a mock up of the 20pin based 430G2 done in Sketchup
mock up.jpg

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Sun Sep 18, 2016 5:39 pm
by fenrisulfr
Hi

Not much further forward. On the cusp of buying stuff but when I'm not sure. In the meantime I've fiddled some more with the uC PCB. Corrected an error (as far as it would have been if you had jumpered the GND and VCC for a 14 pin device in the 20 pin PCB) Also managed to shave the boards length down 39.7mm. On my shopping list is a SMD piezo transducer 8mm x 8mm x 3mm. I plan to mount this on the component side stood on edge (glued in place) with solid wire coming up to wire it up. I've added a pair of pads for the apogee detect signal just in case it's useful later on.
2sketch.jpg
Also had a bash at the original PCB design for this thread. It consists of three boards, 2 similar, and one that is the optical interface. The idea is the 2 similar boards are stacked. Solid wires link the power supply and reset traces. flying wires connect the launch detect PCB to the Optical PCB (small PCB) which in turn is connected to the delay/servo driver PCB. Each of the Main PCBs is 22.2mm x 59mm and the Optical board is 19.5mm x 21mm.
555Optical.jpg

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Mon Sep 19, 2016 5:41 am
by anoymous
fenrisulfr wrote:Hi there

Anoymous: your arduino sys looks great. how has it performed?
I didn't have any reference tests to test accuracy, but the prt of the program involving the altitude measurement was taken from a reliable source and our pressure sensor was a good one too, so it should be fairly accurate.
The system actually never failed, all the ptoblems we had were purely because we forgot to change battery every other flight, because or deployment system failed or because we simply forgot to disarm the altileter after a flight/ forgot to arm b4 the flight

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Wed Sep 28, 2016 7:41 pm
by Blenderite
fenrisulfr wrote:Hi

Not much further forward. On the cusp of buying stuff but when I'm not sure. In the meantime I've fiddled some more with the uC PCB. Corrected an error (as far as it would have been if you had jumpered the GND and VCC for a 14 pin device in the 20 pin PCB) Also managed to shave the boards length down 39.7mm. On my shopping list is a SMD piezo transducer 8mm x 8mm x 3mm. I plan to mount this on the component side stood on edge (glued in place) with solid wire coming up to wire it up. I've added a pair of pads for the apogee detect signal just in case it's useful later on.

2sketch.jpg

Also had a bash at the original PCB design for this thread. It consists of three boards, 2 similar, and one that is the optical interface. The idea is the 2 similar boards are stacked. Solid wires link the power supply and reset traces. flying wires connect the launch detect PCB to the Optical PCB (small PCB) which in turn is connected to the delay/servo driver PCB. Each of the Main PCBs is 22.2mm x 59mm and the Optical board is 19.5mm x 21mm.

555Optical.jpg
Any updates? Do you have a completed board design yet? If so I am chomping at the bit to give it a try!

Re: Optical apogee sensor circuit (not reinventing just knackling)

Posted: Mon Jun 04, 2018 12:09 pm
by Bibbleycheese
I had lots of fun designing an optical apogee sensor back in 2010.
There's a video of it working at https://youtu.be/5FmhzGfn0-U
I built it using a PICAXE proto-board and it worked beautifully at ground level.
However it failed every time I launched. :(
After several rebuilds, I concluded that the sensors couldn't tell the difference between the ground and the sky once it left the ground. :?
It taught me some electronics and programming, and these days I'm using a Micro-Bit with a built-in accelerometer to detect apogee.
Good luck with your project. Hope it works better than mine!