Recreating the Estes Transroc

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fuzzoli

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I've started a journey to bring back the Estes Transroc. The idea is to create a copy of the Transroc that is as true to the original as possible. I had one back in the day, but it's been misplaced over the years -- the only thing I have left is the manual.

I have build log over on the EEVBlog as I need to be able to pull technical assistance if need be.

As of this date, I have everything working on a breadboard (the coils are wound on the actual board however). I have an outstanding RF question after which I'll start populating the board. Then I'll need to get the plastic parts 3D printed.

Stay tuned!

-Frank
 

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fuzzoli

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So it's been a while, but I have put a lot of time (and silliness -- explained at the end) into this project since my last post.

I purchased my first 3D printer and have been learning the idiosyncrasies of that new (to me) technology. It took a good amount of time to learn FreeCAD, and to build out the models for the four plastic pieces. I finally have models and prints that go together well (Photo 1).

And Photo 2 shows the parts test fit together.

In all it has been a fun few months learning the world of 3D printing. I believe I'm turning into a 3D monster!
:scared:


The battery clips had to be shaped from brass strips. I put out a query for ideas on how to get "springy" brass. In the end, I just used leftover pieces from photo etch brass sheets and bent the strips into the proper shape (see Photos #3 & #4).

I didn't want to use the board from the breadboard prototype for the real build because I wanted to keep the breadboard version a little while longer in case I needed to troubleshoot (also to play with RC values -- explained later). So I wound new coils onto a new board, this time documenting the steps and gotchas for the instructions I plan to publish. I received some additional photos from RocketGuy over on YeOldRocket Forum, and he pointed out that the two windings of the smaller coil were wound on top of each other (as opposed to one on top of the board and the other on the bottom side). This was an important catch, and I'm very appreciative for the additional photos!

The next step will be to begin soldering the parts to the board. The plan is to follow the same path as in the prototype -- first build out and test the Modulator section, followed by the RF section. Hopefully everything will go together smoothly.

I should note at this point that the plan is to build this version of the Transroc in the "Spin Rate" configuration. In this mode, a photocell is used to modulate the frequency of an audio tone according to the amount of light falling on the sensor as the rocket spins in flight. I think this mode will give the most useful data as from what I understand, the Microphone mode wasn't as spectacular as one would think. Data from this mode should be easy to analyze with current computing power. Since the original photocell of unknown value, the breadboard version is going to be used to figure out good values for C, as well as determine if the photocell needs to be masked (as in the original). The final R & C values will be then used on this build.

Now for some silliness...

Goal #1 in the first post of this thread was "Recreate the physical Transroc as close to the original as possible." That includes the battery! Now, the Eveready 504 15v dry cell battery is no longer available. You can get some on ebay, but I tend to think that after all these years there would be no hope in recharging.

A similar replacement is available now:

https://www.bhphotovideo.com/c/product/1062350-REG/exell_battery_a220_504a_15v_alkaline_battery.html

But wait, that doesn't look like the the original Red and Blue Eveready battery:

https://www.batteriesandbutter.com/504--M504--.html

Hmmm, what do to...

Well, I made a wrapper and BAM! -- instant 1970's Red and Blue!
:box:
(See last photo)

Yes, it's silly, but why not!

Stay tuned!
 

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wonderboy

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This looks like such a cool project. Are you planning on making any of the parts available or offering up a kit?
 

ksaves2

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I made the Foxmitter in the past and it used a Burgess 21.5v battery. Heck, Burgess isn't even out there anymore. Interesting project. Which CB channel you going to use?
Kurt
 

cerving

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You could probably get away with an A23 12V remote control battery. Maybe two for good measure...
 

groupracer

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So it's been a while, but I have put a lot of time (and silliness -- explained at the end) into this project since my last post.

I purchased my first 3D printer and have been learning the idiosyncrasies of that new (to me) technology. It took a good amount of time to learn FreeCAD, and to build out the models for the four plastic pieces. I finally have models and prints that go together well (Photo 1).

And Photo 2 shows the parts test fit together.

In all it has been a fun few months learning the world of 3D printing. I believe I'm turning into a 3D monster!
:scared:


The battery clips had to be shaped from brass strips. I put out a query for ideas on how to get "springy" brass. In the end, I just used leftover pieces from photo etch brass sheets and bent the strips into the proper shape (see Photos #3 & #4).

I didn't want to use the board from the breadboard prototype for the real build because I wanted to keep the breadboard version a little while longer in case I needed to troubleshoot (also to play with RC values -- explained later). So I wound new coils onto a new board, this time documenting the steps and gotchas for the instructions I plan to publish. I received some additional photos from RocketGuy over on YeOldRocket Forum, and he pointed out that the two windings of the smaller coil were wound on top of each other (as opposed to one on top of the board and the other on the bottom side). This was an important catch, and I'm very appreciative for the additional photos!

The next step will be to begin soldering the parts to the board. The plan is to follow the same path as in the prototype -- first build out and test the Modulator section, followed by the RF section. Hopefully everything will go together smoothly.

I should note at this point that the plan is to build this version of the Transroc in the "Spin Rate" configuration. In this mode, a photocell is used to modulate the frequency of an audio tone according to the amount of light falling on the sensor as the rocket spins in flight. I think this mode will give the most useful data as from what I understand, the Microphone mode wasn't as spectacular as one would think. Data from this mode should be easy to analyze with current computing power. Since the original photocell of unknown value, the breadboard version is going to be used to figure out good values for C, as well as determine if the photocell needs to be masked (as in the original). The final R & C values will be then used on this build.

Now for some silliness...

Goal #1 in the first post of this thread was "Recreate the physical Transroc as close to the original as possible." That includes the battery! Now, the Eveready 504 15v dry cell battery is no longer available. You can get some on ebay, but I tend to think that after all these years there would be no hope in recharging.

A similar replacement is available now:

https://www.bhphotovideo.com/c/product/1062350-REG/exell_battery_a220_504a_15v_alkaline_battery.html

But wait, that doesn't look like the the original Red and Blue Eveready battery:

https://www.batteriesandbutter.com/504--M504--.html

Hmmm, what do to...

Well, I made a wrapper and BAM! -- instant 1970's Red and Blue!
:box:
(See last photo)

Yes, it's silly, but why not!

Stay tuned!
yes i would be interested as well in a "kit" if you are proceeding in that direction. I presently have two original Transrocs an A version and a B . The A has the microphone attached, the B is just the "standard" build with out any attachments. I see you have done a lot of great work here to reproduce this fantastic item.
 

UhClem

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Some things to consider:

1) The FCC Part 15 rules have changed since the TransRoc was produced. The manual claims it meets the Part 15 requirements because of limited output power and antenna length. Perhaps fine then but the current rules are based on measured field strength. This likely is in violation of the current rules. Testing would be required to show that it isn't.

2) This is an AM circuit so is prone to trouble. As an example, is that variation due to the photo cell or is it from the transmit antenna moving around and changing the polarization loss.

FM systems work better but of course require something more than the cheap hand held CB radio which was the target at the time.
 

ksaves2

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First of all, the FCC is unlikely going to be looking for or tracking anything on CB. O.k., somebody using an illegal 100+ watt linear amp maybe, but only if the user was obnoxious or interfering with particular users on another service (ie. poorly filtered amp).
A rocket flight is so short that highly unlikely any interference would occur to cause complaints to be filed.

I don't know what the output of the Transroc was but probably less than 100Mw. That's what most "kiddie" walkie talkies were in the past. There were some monster large walkie talkie Midland jobs that could put out 5 watts on the CB band but took a 12v battery pack (8 AA's) and were "supposed" to be licensed. Back in the 60's and I believe the early 70's the limit was 5 watts as long as one mailed their no-exam license registration form to get a CB callsign. Don't know why the FCC dropped it to 4 watts along the way, over the years. I remember back then I never heard anyone use a CB callsign when I monitored the bands with a 100Mw walkie talkie back when I was a kid.

There was a one transistor change out on the Foxmitter that changed the final from 100Mw output to and blistering "illegal" 300mW output. I did the change during the build and the Federal Cookie Cutters didn't come gunning for me. Had much better ground footprint.

I highly doubt an old or new build, unmodified Transroc is going to be violating any rules. I still wished I had that Foxmitter and Minimitter I built so long ago. I found the box and tested both of them after 20 years and they still worked. I lost them in one of our moves thereafter during domicile changes.

Kurt Savegnago
 

cerving

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Some things to consider:

1) The FCC Part 15 rules have changed since the TransRoc was produced. The manual claims it meets the Part 15 requirements because of limited output power and antenna length. Perhaps fine then but the current rules are based on measured field strength. This likely is in violation of the current rules. Testing would be required to show that it isn't.

2) This is an AM circuit so is prone to trouble. As an example, is that variation due to the photo cell or is it from the transmit antenna moving around and changing the polarization loss.

FM systems work better but of course require something more than the cheap hand held CB radio which was the target at the time.
I think that was when they went from 23 channels to 40 channels, AM to FM. Just in time for the big CB trucker fad to fizzle out...

You could do a whole lot more on the HF Ham bands, of course... and 100 mW (or even 5W) out in the middle of nowhere is probably not going to be a problem to anyone. Maybe on 6m, use CW to send out data and your call sign.
 

ksaves2

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I think that was when they went from 23 channels to 40 channels, AM to FM. Just in time for the big CB trucker fad to fizzle out...

You could do a whole lot more on the HF Ham bands, of course... and 100 mW (or even 5W) out in the middle of nowhere is probably not going to be a problem to anyone. Maybe on 6m, use CW to send out data and your call sign.
Yeah,

A 6 meter (50 somewhat Mhz) tracker would be cool. I don't know if the electronics could be miniaturized as such though. I'm not smart enough to consider that.

Kurt (otherwise known as KC9LDH)
 

ChuckH

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I think that was when they went from 23 channels to 40 channels, AM to FM. Just in time for the big CB trucker fad to fizzle out...
FM was never legal for Citizen's Band in the US. Not that you couldn't get an export CB with FM if you were so inclined ;)

Sorry for the thread hijack...
 

cerving

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FM was never legal for Citizen's Band in the US. Not that you couldn't get an export CB with FM if you were so inclined ;)

Sorry for the thread hijack...
I stand corrected... I thought that was one of the reasons for the channel change, to reduce the amount harmonic interference.
 

cerving

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Yeah,

A 6 meter (50 somewhat Mhz) tracker would be cool. I don't know if the electronics could be miniaturized as such though. I'm not smart enough to consider that.

Kurt (otherwise known as KC9LDH)
There are some 50.350 MHz SMT oscillator modules around that could easily be used to create a CW beacon. They're small, and they're cheap (under $2). Throw in a small processor to control the modulation, a bandpass filter to get rid of the harmonics (since it's a square wave output), and a small Class 1 amplifier and matching network, and you can probably fit it on a board 1/2" x 1" if you try. A single 110 mAH 1S Lipo would run it for a long time.
 

ksaves2

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There are some 50.350 MHz SMT oscillator modules around that could easily be used to create a CW beacon. They're small, and they're cheap (under $2). Throw in a small processor to control the modulation, a bandpass filter to get rid of the harmonics (since it's a square wave output), and a small Class 1 amplifier and matching network, and you can probably fit it on a board 1/2" x 1" if you try. A single 110 mAH 1S Lipo would run it for a long time.
The problem might be getting an effective antenna that was doable on a rocket so me thinks. Kurt
 

ksaves2

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FM was never legal for Citizen's Band in the US. Not that you couldn't get an export CB with FM if you were so inclined ;)

Sorry for the thread hijack...
Though on the 10 meter Ham radio band FM is legal. Says so on my radio. CB is 11 meters. I once picked up a 10 meter repeater from New York city on an H/T when the propagation gods were smiling one afternoon. No, I couldn't transmit with the H/T on that band but I could receive. If I could have, I doubt 5 watts would have made it in from central Illinois on an H/T.
Kurt Savegnago
 

UhClem

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This thread reminded me that once, long ago, I purchased an FM transmitter kit for reasons that I can't recall. It has gathered dust every since. A quick search turned up something that looks a lot like it:

KIT 32

Designed to operate near 100MHz, aka the FM broadcast band.
 

ksaves2

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This thread reminded me that once, long ago, I purchased an FM transmitter kit for reasons that I can't recall. It has gathered dust every since. A quick search turned up something that looks a lot like it:

KIT 32

Designed to operate near 100MHz, aka the FM broadcast band.
Sheeeeeoooot, I built a couple of those!! One is still out in the garage. Problem is one had to turn a pot on the board to tune it "so's not to interfere" with commercial FM stations. What a PITA.
I did learn how to solder components in kits though! :) Never did fly one but dang, downstairs in the basement, the sound quality was freaking good. The radio upstairs picked up my feet walking across the floor with a little stinking microphone.

They were unstable as when the battery started to die down, the frequency drifted off. That is the main reason I never flew one. Got into Ham radio and went from there. Crystal controlled or with feedback circuits is the way to go. I've never had an issue with modern trackers, APRS or otherwise whatsoever.

I still like my Beeline GPS trackers. Very easy to pipe the datastream to a mapping program to live track a rocket with the right equipment. With the new cheaper 2 meter APRS trackers out there, Ham guys who fly rockets can do some dastardly neat tracking as long as they have a rocket with a long enough nosecone to contain the tracker. Otherwise the 70cm (400Mhz) trackers are better suited.

My original goal was to pipe the data output to a mapping program to a handheld or a tablet to get a rocket back. I achieved that and am itching to get out there again.

APRS or Eggfinder I got it on a live map to track.

Kurt
 

ksaves2

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Ahhhh, I found one of the FM radio kits I built so long ago.


Looks like they're still in business but I don't recommend this to fly as it's not that stable in frequency as the battery runs down. Still was a lot of fun to learn soldering back in the day.

Kurt
 
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