Altimeter Status Indicators...

I decided to make a how-to as I go along on this project. The scope is to add slave LED's to all of my altimeters that are AT the surface of the airframe so that I don't have to spend minutes trying to find the LED that is mounted on the altimeter. The reason I rely on these LED's is that I am profoundly deaf and cannot hear the sound of the piezo buzzers that are mounted on today's altimeters.

As part of this project, I have an assortment of altimeters - Adept22, SL-100, MARSA54L, and a RRC3. The Adept22's were converted by removing the piezo and installing a LED and resistor per Tommy's suggestion. The SL-100, MARSA54L, and RRC3 have auxilary outputs that are designated (or can be used as) slave LED drivers.

I acquired Red, Blue, and Green LED's from Mouser as well as a batch of 1k Ohm resistors. I also have a bunch of WS Deans micro connectors that I enjoy using for this type of application, and used 22ga stranded wire for this application.




You can see the end result of the project. The above coupler is for the Black Brant 2 which uses a slide-in av-bay (vs the conventional coupler av bay), hence the reason for standalone setup.



To start, I protected the paint with some blue tape, and determined where the rivet holes are (holes circled with sharpie) as to determine best location for this setup. I marked the outside of the av bay as well as the inside (it helps to extend the lines to the end of the couplers so you can use those as a reference for your inside line). I used a piece of 1" 90* angle aluminum.



I located the holes with a center punch/scribe at 3/8" intervals (my LED spacing).



I then drilled the holes using a small drill bit (appears to be 3/32", but you can choose whatever diameter you like). I didn't want to enlarge the holes too much.



Next, I had to prepare the LED mount. In this case, I used what I think is 3/8" square basswood. I cut them at 1-1/2" long, and made marks every 3/8" for drilling. I used a scribe to prick the centerpoints for drilling as well.



I used the same 3/32" drill as a pilot hole for the larger drill in the next step. I let the drill do the work so that the hole won't run off center through the part.



I used a #10 drill which is a 0.203" diameter drill bit, which matches up with the diameter of the LED. I wanted to ensure a decent press fit so that it could be replaced but won't fall out with a simple puff of air.



I cut the part at 1-1/2" long as stated earlier. Obligatory "step completed" photo here.



You can see how the LED fits in the block. It's a nice press fit.

To be continued....

I needed to mount the LED block to the coupler wall, so I scuffed it up with some sandpaper and cleaned it with some acetone.





One of the things to remember when you're mounting the block is that you want your LED block centered up on the holes drilled through the coupler.

In order to accomplish this, I took the block, placed it outside of the coupler and aligned it such that the holes in the mount were concentric with the holes in the av bay. While doing this, I measured from one end of the block to the end of the coupler so that when I epoxied the block in place, I could measure the block and ensure that I'd be pretty close if not dead on. There is enough of a viewing angle on the LED to still illuminate through the holes even if you are off by a little bit.



I whipped up some epoxy and spread it on the face of the LED block and then placed it inside the coupler.





Since I had to wait for epoxy to dry, I decided to start preparing the LED's. I made up some harnesses. The LED is wired directly to the plug. The other half of the harness features the plug wired to a resistor, then a pigtail which can be wired to the altimeters. I wanted to keep the LED half of the harness such that it could receive the full current, and I could adjust the current being sent to the LED by means of the other half of the harness. The MARSA54L is already set up for the LED's I have, so no resistor is needed. I will make up a harness without a resistor that way. I'll sketch up a schematic later when I have time.



Kind of getting ahead of myself here, but here is what it looks like with the LED's in place (the BBII av bay was epoxied up the other night, hence why I was able to mess around with this one today). The photos at the beginning of this thread show the viewing side and how bright they are. Once the av bay board is made up, I'll show what it looks like when completed and installed in the rocket.

To be continued....!!!!

Very nice, I prefer visual indicators also.

Thanks! I hope you and others can draw inspiration from this. I am sure smaller LED's can be used (or even flush mount LED's...). Most of my rockets have some room in the av bays so I'm not too worried about space. I did realize when I was checking things out tonight how long I made my leads. I figured 20" should give me some wiggle room... But my av bay for the BBII is 8" long, Last Call is 9" long... Yikes! Maybe I will shorten them, or use the first batch of leads for the WAC Corporal.

Mike

I have been looking at the flat top LED's to give them a flush and finished top as it comes through the Av Bay. I have also considered having the power up switch mounted into the shoulder of the Av Bay as it would be hidden after arming. still not sure exactly how much any of our attempts at making it aerodynamic really matter unless trying a Mach+ flight.

My next step on this project is to surface mount the LED's. I did this with the WAC Corporal, it worked out OK... But there is lots of room for improvement. Just placed an order with McMaster so that should give me a way to make progress on this front.

The problem with led is that they add additional wirring in your payload so whenever you want to open it, it takes more time.
In one of my altimeter I have added the possibility to change the buzzer frequency. I did it for a friend of mine who cannot hear all frequencies so that he can change it to something he can hear.
https://rocket.payload.free.fr/index.php?option=com_content&view=article&id=13&Itemid=11&lang=en
Are they any frenquencies that you can hear better than other?

Some of the altimeters I have have that feature, and I could BARELY hear the difference. That does pose a problem when I'm at the field and wind is gusting over my hearing aids thus causing a fluttering/feedback on the microphones of my hearing aids.

The way I see it, yes, it causes more wiring. Yes, more connectors. But I would prefer to have 100% visual indication available than a lawn dart because I thot I taw a putty tat... Er.. Saw the LED's. Some of the LEDS are the same color, which could pose a problem also. I'd rather spend an extra minute or two to wire up the LED's at the field than not. Remember - "Go Fever" is not always good. I also do as much prep as I can ahead of time..

Well done! Elegant and tasteful. Very much dig this.


Later!

--Coop

Nice idea to make the indicators easily visible.

mrwalsh85 said:

I needed to mount the LED block to the coupler wall, so I scuffed it up with some sandpaper and cleaned it with some acetone.

Click to expand...

By the way, it's better to clean the surface before sanding, otherwise the sanding grinds whatever would have been cleaned off into the grooves created. Not that it really matters for this application, but just a reminder about bonding to fiberglass.

mrwalsh85 said:

Some of the altimeters I have have that feature, and I could BARELY hear the difference. That does pose a problem when I'm at the field and wind is gusting over my hearing aids thus causing a fluttering/feedback on the microphones of my hearing aids.

The way I see it, yes, it causes more wiring. Yes, more connectors. But I would prefer to have 100% visual indication available than a lawn dart because I thot I taw a putty tat... Er.. Saw the LED's. Some of the LEDS are the same color, which could pose a problem also. I'd rather spend an extra minute or two to wire up the LED's at the field than not. Remember - "Go Fever" is not always good. I also do as much prep as I can ahead of time..

Click to expand...

Would you be interrested if you could check the status of your rocket from your phone?

First off, very cool project! I've been intrigued about doing something like this myself.

Second, sorry about your hearing troubles, but I don't think any one of us finds straining to hear those tiny beepers embedded deep in your rocket on a windy day when someone is talking over the PA system (or worse, playing music) easy. My hearing is none too good anymore and it's a real pain to know for sure I'm hearing my altimeters correctly.

I haven't implemented it yet, but here is my idea on dealing with the same problem: Install a tiny microphone inside the payload bay, and connect it to a jack on the outside of the rocket. Carry a pair of headphones or one of those tiny Radio Shack amplified speakers in your pocket and hook it up when you need to verify. Once you know you're good to go; unhook and get out of there.

Yes please ,Android.

bdureau said:

Would you be interrested if you could check the status of your rocket from your phone?

Click to expand...

bdureau said:

Would you be interrested if you could check the status of your rocket from your phone?

Click to expand...

That's what you get with Altus Metrum altimeters that have telemetry; you can check your rocket status from LCO with your android phone, amateur radio or laptop. And, you keep getting this information for the whole flight...

I don't see a need for the bluetooth assistance. The reason for 3 LED's (R,G,B) is to be able to differentiate between altimeters. Having a phono jack would defeat this purpose.

I won't need to bring anything to the pad with me but a screwdriver, masking tape and an igniter. If I leave the phone at the car, a phone call can wait a few minutes.

Anxiously waiting on UPS to come tomorrow...

LED's ARE telemetry at 600,000 GHz, no ham license or FCC certification required either. Also a very reliable system with great link margin.

Additionally the receivers are very economical, extremely reliable and the included processor is the most powerful computer in the world.

If you want a flush look, you can fill the holes in the airframe with unpainted epoxy. This acts like a little diffusion lens and the led shines right through. I suspect you could detect the glow behind unpainted green fiberglass tubes (certainly not the new-fangled colored tubes which are mostly opaque), but I haven't checked it. I would drill the holes. Put tape on the inside of the airframe and fill the holes with epoxy. Remove the tape and sand the outside flush. Then use little circles of masking tape over the epoxy before painting so they don't get occluded.

Kevin

On my latest two rockets I just drilled a 0.190 hole in the airframe and pressfit the LEDs into the holes. One was FG the other was BlueTube.

jderimig said:

LED's ARE telemetry at 600,000 GHz, no ham license or FCC certification required either. Also a very reliable system with great link margin.

Additionally the receivers are very economical, extremely reliable and the included processor is the most powerful computer in the world.

Click to expand...

That's awesome! Now if the manufacturer could be convinced to provide warrantee maintenance on mine; they just don't have the range they used to...

I have been considering mounting external LEDs as well. The Eggtimer has connections for them on the board, just solder an extra wire & add connectors. It also has an external buzzer connection that I am sure could be adapted for an LED as the OP discussed....

I've often thought this would be a good solution to being able to hear the beeps...

I've heard that too, Al. Problem is any wind gusts can be picked up by the stethoscope as well. Wouldn't work in my situation regardless.

Got all my hardware today. I'll be in the shop tomorrow!