# What did you do rocket wise today?

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#### JoePfeiffer

##### Well-Known Member
if it's really cold you've got yourself a rock band.
For decades I thought they were from Australia...

#### Wally Ferrer

##### SRE
TRF Supporter
No, I can't. You've sent me down a rabbit hole that led to reading up on the Australian pre-decimal coins. did you know that the crown fits nicely into a 38 mm MMT?

(It's odd, I'm not a coin collector, and never have been. But I can't help reading about systems of coinage: the denominations, alloys, dimensions, and occasional trivia.)
Coins in Ocean City Maryland has the best crabcakes.

#### jqavins

TRF Supporter
(It's odd, I'm not a coin collector, and never have been. But I can't help reading about systems of coinage: the denominations, alloys, dimensions, and occasional trivia.)
Coins in Ocean City Maryland has the best crabcakes.
Crab, 80%
Onions, 5%
Crab juice, 3%
Vegetable oil, 2%
Seasonings, trace.

One of my favorite alloys.

#### Cape Byron

##### The BAR formerly known as Skippy-2
TRF Supporter
No, I can't. You've sent me down a rabbit hole that led to reading up on the Australian pre-decimal coins. did you know that the crown fits nicely into a 38 mm MMT?

(It's odd, I'm not a coin collector, and never have been. But I can't help reading about systems of coinage: the denominations, alloys, dimensions, and occasional trivia.)
Ah, pre-decimal currency. We have a small collection.

Decimal currency came in on Valentines Day, 1966. In the lead up there was a television commercial an an animated dollar bill, imaginatively called 'Dollar Bill' and a pretty snappy jingle. We had a mix of decimal and pre-decimal coins in circulation for what seemed like years. Shop listed prices in both currencies.

People hated the new notes because they were much smaller than the old ones. Colourful, by the standards of the day, lead to the notes being treated as play money by many children.

If you have any crowns, their minimum value is about $75. Some fetch thousands. #### jqavins ##### Helpful Smartass TRF Supporter New money Always looks like play mony to the people who are used to the old, and people always object to it. We introduced new paper money designs here quite some years ago now, with bigger portraits, a slightly different layout, and a little color; same size, material, and general design as before, and people went nuts. In time, as also always happens, people got used to them and no longer give them a thought or second look. Longer ago, we introduced$2 bills that were so widely rejected that there are people today who'll think they're fake if they ever see one. (There have been arrests on very rare occasions.)

Our government would like to stop printing $1 bills, and go to dollar coins. The public objects, and the government gives in. How about introducing the dollar coins first so people can get used to them and then remove the bills? Nope, people reject the play money coins and the bills continue. There are about a billion$1 coins sitting in bags that Congress ordered made but no one wants.

How about introducing twos so we won't need as many ones? Nope they don't like the twos either.

We could stop printing ones if we'd do one simple thing: stop printing ones. As always, people would get over it and get used to the coins. I'd be happier if a $2 denomination also came out, be it paper or metal, because I'd rather not have so many 8 gram$1 coins in my pocket. (Actually, the law is still on the books that allows the printing of twos, and small runs of them have been made from time to time, so it'd be easy step that up. A new coin would have to be approved by Congress.)

#### Cape Byron

##### The BAR formerly known as Skippy-2
TRF Supporter
We have $1 and$2 coins, commonly referred to as 'gold coins' by people seeking a donation. They're about as close to gold as aluminium foil.

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#### neil_w

##### Marginally Stable
TRF Supporter
The design wraps around the rocket more than once, so it takes some, umm, creativity to get on there.
I hadn't even thought of that aspect... Could the mask cut into two pieces (an adventure unto itself) so that each piece is less or equal to one full wrap?

Would like to see video how you did that.

#### jqavins

TRF Supporter
It seems like both I misread something, and perhaps you misstated something else.
I also ordered a 4s lipo and a drone power distribution board to play around with.
[Underline added] My eyes skipped over that part, and I thought you were running off two taps from a series stack of cells. Which would surely increase noise linking between the two devices. But a dcent distribution board which has some sort of output buffering (like two entirely separate DC/DC converters) should give excellent isolation.
I'd also like them to not electrically interfere with each other.
Which makes it seem that noise reduction was your goal, or at least part of it. With the power distribution board you're still not getting any better than two separate batteries, but no worse either.

#### Cl(VII)

##### Chris Bender, Lab Rat
It seems like both I misread something, and perhaps you misstated something else.[Underline added] My eyes skipped over that part, and I thought you were running off two taps from a series stack of cells. Which would surely increase noise linking between the two devices. But a dcent distribution board which has some sort of output buffering (like two entirely separate DC/DC converters) should give excellent isolation.Which makes it seem that noise reduction was your goal, or at least part of it. With the power distribution board you're still not getting any better than two separate batteries, but no worse either.
Simply put, I'm looking to power many things (with different input voltages) off one battery while not introducing an intolerable amount of electrical noise. Intolerable defined as impeding safe function, or resulting in damage.

#### HHaase

##### Siegecraft Electronics
Looking at that board, I see two discreet voltage regulator systems. Are the ESC outputs are regulated at all Or are they simply pass-thru for the battery voltage? I wonder what the outputs would look like on the scope for the regulated outputs.

A lot of stuff going on with that little board. Even connects the camera output to the transmitter input..... so FPV rocket!

-Hans

#### jqavins

TRF Supporter
Simply put, I'm looking to power many things (with different input voltages) off one battery while not introducing an intolerable amount of electrical noise. Intolerable defined as impeding safe function, or resulting in damage.
And I pronounce your solution sound.

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#### Cl(VII)

##### Chris Bender, Lab Rat
Looking at that board, I see two discreet voltage regulator systems. Are the ESC outputs are regulated at all Or are they simply pass-thru for the battery voltage? I wonder what the outputs would look like on the scope for the regulated outputs.

A lot of stuff going on with that little board. Even connects the camera output to the transmitter input..... so FPV rocket!

-Hans
Near as I can tell they are pass-thru. It is pretty unlikely that I will use those as there are four feed for 5V and/or 12V (one BEC each, and the video power pads).

#### HHaase

##### Siegecraft Electronics
Near as I can tell they are pass-thru. It is pretty unlikely that I will use those as there are four feed for 5V and/or 12V (one BEC each, and the video power pads).
Just make sure to measure the 12v output if you're using it, particularly with a 3S battery. Depending on the regulator they used it may not output the full 12v with less than a 4S.

-Hans

#### Cape Byron

##### The BAR formerly known as Skippy-2
TRF Supporter
Joy in the mailbox. My LiPo batteries and charger arrived in the mail. Time to do some soldering...

Horizon Models WRESAT arrived to challenge my PMC skills. I'll unbox it after doing some more chores.

'Two-up' got a well deserved paint job to go with her stock nose cone. I'll ask the local Fire Brigade Captain for a burn permit next week. I have prototypes to test!

#### OverTheTop

##### Well-Known Member
TRF Supporter
I hear you, but part of what these boards are designed to do is minimize that interference in racing drones. Our stuff is pretty constant drain, especially compared to four drone motors. The exception would be on deployment charge firing, and that should be low current too with ematches unless there is a short. I'm doing this more in an effort to see how much I can cram into a small space than to reduce interference. I'm looking at it the other way, i.e. is the increased interference and loss of battery redundancy worth the space and wiring complexity savings in crammed electronics bays. When designing things to fit in 38mm rockets, the batteries are often the most frustrating part. I want to see if I can fit a camera, 2 altimeters and a tracker in one 38mm bay that is about 8" long...I think I can if this works, it will certainly be easier.

If nothing else it will be a cheap (\$13) learning experience.

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There are nice big pads on the periphery of that PCA, with grounds next to Vcc/5V/12V. One of the ways they save money in these things is to get away with the minimum number of capacitors. You can easily add some SMT caps across those conveniently placed pads. This will additionally decouple each supply from the source, as well as shunting any RF pickup on the leads (aka antennas) exiting the board. That should reduce any internal EMC problems greatly. I would think caps around 10u or 22u would be a reasonable guess. Note that typical ceramic capacitors of those values have dielectrics (like Y5V) that are highly voltage dependent. The higher the voltage the lower the capacitance. So a nominal 22u cap might end up more around 10u around the maximum working voltage. The two takeaways from this are; check the data sheet, and use a higher rated voltage to minimise this drop. If you use C0G or X7R capacitors this reduction is minimal or nil. In the capacitances needed these will not be available in those nice dielectrics.

Personally I would be adding capacitors to at least some of those locations. YMMV