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Aug 27, 2019, 07:41 PM
My 1st R/C had 2 valves !
KraftyOne's Avatar
Quote:
Originally Posted by JMP_blackfoot
Here is the last page
Thanks for that...
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Sep 08, 2019, 12:34 AM
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HIR/Cer's Avatar

More eBay recently completed


Sign of the times, perhaps.
Sep 08, 2019, 05:30 AM
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The PIPE's Avatar

The "hardware" for the Luftwaffe was the "Kehl" Tx, and the "Strasbourg" Rx...


Dear JMP_blackfoot:

The PIPE Here again - as I'm also an amateur historian concerning aviation through 1945 (why ELSE would I love RC Scale subjects before 1945, hmm?) your "below note" about the Nazi-era Luftwaffe Fritz X armored gravity PGM, and the rocket-boosted Henschel Hs 293 unarmored glide-bomb (from the same firm that made THE Tiger tanks), prompted my reply:

Quote:
Originally Posted by JMP_blackfoot
TTPW-CAR stands for "Two-Tone Pulse Width" - "Coupled Aileron Rudder".
TTPW is a double simultaneous pulse proportional system plus trimmable throttle [not used in the mentioned German RC system) which is not unlike the system used by the Germans during WW2 for their guided bombs.\
...the German Funkgert (FuG) 203 transmitter was named for a suburb (Kehl), of the major French eastern border city of Strasbourg, itself giving its name in German (Straburg, for the "eszett" or "doubled/sharp S") to spell it properly, for the ordnance item's "matching" FuG 230 receiver.

It was the Fritz X armored, 1-short ton gravity bomb that used the so-called "TTPW" style of RC, as it used two sets of rapidly oscillating "spoilers" in its tail under direct control from the FuG 203 "Kehl" Tx in the bomber, to guide it both laterally, and control its range; from the sets of spoilers in the tail of the bomb, which had a "stretched-laterally" dodecagon-shape annular ring around them, allowing an extra set of "outboard" horizontal-axis spoilers operating from a roll-control gyro in the bomb's tail (and NOT from the Kehl Tx) to keep it level during its guided descent from the bomber. By contrast, the rocket-boosted Henschel Hs 293 had no such tail-gyro, and by contrast with the Fritz X's implemtation of the very same control hardware; had a "bang-bang" set (full-throw ONLY) of non-proportional ailerons on its monoplane wing panels, with a proportional, screwjack-style servo operating its elevator function.

The Fritz X's style of using the Kehl-Strasbourg hardware was much more like the "galloping ghost" style of RC gear with its triple set of "buzzing spoilers" (the roll gyro's spoilers also "buzzed" in the exact same manner!) - there used to BE an available-on-YouTube, captured German film on the Fritz X ordnance that the linked and annotated image of the Fritz X's tail controls is from, where you could see all that happening - that was ILLEGALLY copyrighted by the "Critical Past" private firm not very long ago to "make some money" - the US government NEEDS to prosecute that firm to return those sorts of films/videos to their proper "public domain" status, as being from the US National Archives, and freely available once again for historic study, as official works of the Federal government, which were NEVER intended to be "copyrighted" by anyone.

Hope this helps in understanding what you'd hinted at with that paragraph I quoted...!

Thanks and Yours Sincerely,
The PIPE....!
Last edited by The PIPE; Sep 08, 2019 at 03:50 PM.
Sep 08, 2019, 11:23 PM
My 1st R/C had 2 valves !
KraftyOne's Avatar

Kraft 3C Tx "before & after".


Just finishing up the KPT-3C conversion, these are a "before" and some "after" pics.

The throttle stick mounting has been rotated for easier trim lever access.
As the battery meter was O/C, it has been replaced by a digital readout.
The Futaba style Assan module sits above the throttle stick, still in its original case.

The battery case contains a single 18650 Li-ion cell, (fitted with a protection board), driving an 8V boost regulator. Also included is a charge control module allowing a 5-15V input. I normally use a USB outlet to charge. (They are everywhere now days)...
Sep 09, 2019, 09:49 AM
Registered User
I like the way you did the battery, keeping it in the original case!
Sep 09, 2019, 12:12 PM
ƃuıʇɐǝʞ ʇʇoɔs
vulturetec's Avatar
Quote:
Originally Posted by KraftyOne
The battery case contains a single 18650 Li-ion cell, (fitted with a protection board), driving an 8V boost regulator. Also included is a charge control module allowing a 5-15V input. I normally use a USB outlet to charge. (They are everywhere now days)...
When I gutted my KPT-2/3S I had lots of room and ended up using a 3-cell LiFePo4 pack, but I like the single 18650 cell as an option.

Question: I've always been hesitant to use a boost regulator board in these types of applications with older encoders (but then I have to admit I just haven't tried it either). I'm curious how clean the DC is coming out of the board, particularly when the battery starts to run down a bit. Have you looked at it on a scope or otherwise added any filtering at the encoder?

If the efficiency losses aren't bad and the DC is clean, even using just half the capacity of a 3000mah cell should run the average Kraft radio for a good long time. Seems like a good alternative, especially when it fits in the original battery box.
Latest blog entry: Sagitta 600 build 2018
Sep 10, 2019, 02:54 AM
My 1st R/C had 2 valves !
KraftyOne's Avatar
I started using boost regulators around 5 years ago, and did check with a scope at the time, can't remember the figures, but ripple was negligible. I do always replace the main filter cap on old encoder boards, usually with a similar physically sized new unit, which means it has higher capacity than the original, (to be sure, to be sure)...

The 1st one I built is still in one of my 7Cs, it does not have a protection board (yet), and the reg is an earlier 10A unit, so no worries about overstressing it... The latest units have a new smaller 2A reg, and a protection board with balance charge function, requiring just a 9V input to charge.

The KPT-3C is the first time I have used a single cell, and it seems to be working OK. I've haven't run any time checks yet, only used it for a few short flights to date, the battery was not fully charged and still shows over 3.9V. The reg specs show a 2-24V input range.

https://www.banggood.com/DC-Boost-Co...r_warehouse=CN
Sep 10, 2019, 12:02 PM
ƃuıʇɐǝʞ ʇʇoɔs
vulturetec's Avatar
Excellent info, thanks!
Latest blog entry: Sagitta 600 build 2018
Sep 17, 2019, 08:31 AM
Registered User
I could use help repairing my Kraft Series 80 5C Tx aileron control. Problem is the trim lever is very stiff. I can't figure out how to remove the pot and trim mechanism. I loosened 3 screws but it won't budge.
Sep 17, 2019, 12:27 PM
ZR, OOS in a trash lifter
jmendoza's Avatar

Bucking regulator issues


I gave up on using DC-DC converters as regulators for discrete encoders due to the servo jitter problems they cause. Some of the later IC type encoders are not affected, but I have found that the LM-317 adjustable linear regulator modules never give me any issues so I use them. In addition, you only need the regulator for the encoder, which draws very little current so any advantage the switching/bucking regulators give you is negligible in terms of reducing current draw.

The primary issue is due to the switching frequency and sharp rise times of the square waves produced by the "chopper" circuit of the DC-DC converter used in these regulators. The resultant noise spikes they produce can false trip the one shots in the encoder resulting in random servo twitching. A linear type regulator, while not as efficient , completely eliminates these issues. It is enough to have the switching noise from a 2.4 GHz module, which is why a regulator is needed in the first place, but a second noise source, meaning a switching regulator doubles the equation.

Using a very low impedance battery, with very large capacity will reduce this issue (lead acid 12V 5 Ah motorcycle type) but that is impractical.

Replacing the original encoder with an Arduino eliminates the need for any voltage regulators and gives you a bunch of modern features as well...it is the way to go. At least that is my experience, others may have a different point of view.

Jay
Sep 19, 2019, 11:58 AM
Registered User
JMP_blackfoot's Avatar
Quote:
Originally Posted by LedZepplin
I could use help repairing my Kraft Series 80 5C Tx aileron control. Problem is the trim lever is very stiff. I can't figure out how to remove the pot and trim mechanism. I loosened 3 screws but it won't budge.
This may help you:
https://www.vintagercfiles.com/Files...nual_76-79.pdf
Sep 19, 2019, 12:00 PM
Registered User
JMP_blackfoot's Avatar
Quote:
Originally Posted by jmendoza
Replacing the original encoder with an Arduino eliminates the need for any voltage regulators and gives you a bunch of modern features as well...it is the way to go. At least that is my experience, others may have a different point of view.
Jay
+1
Sep 19, 2019, 03:29 PM
Registered User
Quote:
Originally Posted by JMP_blackfoot
Hey thanks JMP, lotta good stuff here!

Zep
Sep 20, 2019, 04:26 AM
My 1st R/C had 2 valves !
KraftyOne's Avatar

Bucking regulator issues


Hi Jay.

I havn't used regulators with the old One-shot/Half-shot encoders so was not aware of the issues there, and the latest switching regs are much smoother than the early models so it may not be a problem now. Because I need boost regulators to do what I do, a linear reg is "off the menu" for my purposes. The Sig/7C encoder does NOT like ripple, and works fine using the buck-boost reg, 7.5-8V to 9.6V, and a new Lo-ESR filter cap takes care of any spikes, (havn't seen any when testing), but my O'scope is a bit old and slow... (like its' owner).

I do not replace encoders in post '76 Kraft radios (unless they are faulty), that's not the purpose of my restorations. I have several modern radios with all the bells and whistles, Futaba, Multiplex, Turnigy, AND a Kraft/Spektrum DX-7SS, I don't need any more. I have done a few Kraft pre-'76 conversions for others using the excellent Ron Ellis encoder, but havn't ventured into Arduino territory yet, (not sure if I've got the time left to get a handle on it)...

For reasons I have mentioned before this, I do not want to use nicads, leaky old tech, Li-ion rules now, but I do not want to cut up the Tx battery cases, especially when using the original encoders, as they mount on the cases.

And that's why I do what I do. Everyone else will do what they want to do, and that's fine.

Eric.
Sep 20, 2019, 12:27 PM
TAFTS
Technically, as soon as you replace the batteries with Li, its not original anymore. But I totally support any level of restoration/refurbishment/repair. I think its cool people save them and make them usable again. People like Eric and Jay that know how those old encoders work are few and far between and are fading. So its great you guys work on that stuff.

Eric, it would take you a day or two to learn enough about the Arduino encoders to use them effectively. I think they are a great way to bring reliable life back into the old radios. But that's me. And the beauty of our hobby is we all get to do things different ways and enjoy it. So keep doing what you do and keep posting!


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