New Nano Speed Controller

[toppack]

It's very simple to make a stand-alone BEC, using LM7805 IC and a heatsink. Only 3 wire connections, In, Out & Gnd. Cost less than $3. for the IC. It has TO-220 package design which has it's own grounded mounting tab, for attaching to heatsink.
Of course with it also, it depends on how large a Heat-sink you attach to it and how well it's ventilated, which determines it's current handling capability.
They are so easy to connect up and cost so little you could use a different one for each servo if needed. :) Since they are so small without a large heatsink attached.

[Subculture]

The 7805 will work okay, but don't use them on a 6 volt system, because you'll experience problems. Unless the linear regulator is of the low drop out variety, they need at least 2 volts above the required regulated voltage to work properly, i.e. 7 volts for a 5 volt output.

A low drop out regulator is far more tolerant, i.e. LM2940 which only requires 0.5 volts above the regulated voltage.

Switch mode BEC's are very tolerant of voltage levels. The one that John is using I have found will work well outside of it's spec. I've succesfully run it on just one Li-po cell (3.8v) and from a 24 volt power supply, and the output stays rock solid.

[toppack]

The 7805 will work okay, but don't use them on a 6 volt system, because you'll experience problems. Unless the linear regulator is of the low drop out variety, they need at least 2 volts above the required regulated voltage to work properly, i.e. 7 volts for a 5 volt output.

Yes, that's true. That's another reason I've always tryed to use only 12.volt batteries in my models, to eliminate potential problems like that. A 12.volt battery has to be almost dead before it gets below the operating voltage of the components it's powering.
Of course I realize you can't always use a 12.v, in some models with very limited space and weight.

[Subculture]

You can also get 3 amp 5 volt regulators like the LM323.

[toppack]

You can also get 3 amp 5 volt regulators like the LM323.

Yes, they are rated at a higher current but I don't think the LM323 is available in the Handy-dandy TO-220 single-tab package? Only the much larger TO-3 type can, which is also more difficult to mount on heatsink, since it requires 4 holes drilled instead of 1.

[Subculture]

In that case have a look at the TS1084- http://www.maplin.co.uk/Media/PDFs/Module%2046054.pdf

[toppack]

Oh yeah! I like the looks of that 5.Amps.
It probably requires a large heatsink with good ventalation to handle that 5.Amps, for very long, but it certainly reads like it would out perform the 7805.
I didn't check the price and availability but if there's no problems there, that may be a Good one.

[Subculture]

You have the best heatsink all around you with a submarine. If you had a metal endcap, instead of resin, then that would make a great heatsink that could take a heck of a lot abuse.

The regulators are £1.30, and you can probably find them a lot cheaper than that (Maplin are quite expensive).

http://www.maplin.co.uk/Search.aspx?criteria=voltage%20regulator&source=15

[toppack]

You have the best heatsink all around you with a submarine. If you had a metal endcap, instead of resin, then that would make a great heatsink that could take a heck of a lot abuse.

David & Mike,
How much would you charge for a machined aluminum end-cap, with O-ring groove, for my 3.5" SD?
(no holes needed in it, I can do that)

Or should this go in the 'Silly Questions' forum? ;)

[toppack]

Well, I was going to check the price of the TS1084 at Newark, but their data shows that the output voltage is Only 3.3 volts (Not a 5.v version), so I'm not sure about it any more?

[Subculture]

5 volt definitely available. Digikey stock it-

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=AP1084T50L-UDI-ND

Unfortunately electronics are getting harder to find now other than through mail order. People aren't making their own circuits anymore, and this is understandable when you see the commercial offerings with neat little SMD components, ill-suited to DIY construction, but which make items much more compact and reliable.

Digikey stock just about everything under the sun, and their prices are good too. Unfortunately you need to make a minimum order. Best way around that is to order quite a few up, make up some extras, and flog 'em on to other modellers.

[zeusbheld]

The Nano speed controller looks like a good option for my 1/72 PT boat. How much does it weigh? The Mtronics version with the epoxy housing weighs 23g; I'd imagine that the speed controller without the housing weighs a lot less.