Best way to drop 21v to 9v please

[Tony]

So there are no stupid questions just ------------------

I've started rebuilding some of my many acquired unfinished projects... first is a Garrett using 2 x lgb 2085 blocks, I have fitted a 21v battery and Revo RC all working great. sound wise as i have a box full of Bachmann simple sound cards yes i know they are [strike]C**p[/strike] Rubbish but to save on cash they will do for now

Question is as they are 9v..... which is the easiest (read cheapest) way of powering them

i can fit a 9v battery in each unit but would like to power them from the 21v as it is rechargeable though a socket.....They both will use reed switches via the wheels of each unit.

If i connect them in series is that going to be enough to stop them becoming a third smoke unit

 

[nicebutdim]

If you're much good with a soldering iron use a voltage regulator chip like this one http://www.ebay.co.uk/itm/2A-POSITI...al_Components_Supplies_ET&hash=item2c6af1353d < Link To http://www.ebay.co.uk/itm...mp;hash=item2c6af1353d which only needs a couple of other components to operate. The simpler idea could be to use one of these http://www.ebay.co.uk/itm/5V-9V-12V...al_Components_Supplies_ET&hash=item27d18f5594 < Link To http://www.ebay.co.uk/itm...mp;hash=item27d18f5594 which basically uses the above chip in a ready made circuit.
Here is a link to the circuit using the L78S09CV regulator http://www.google.co.uk/imgres?hl=e...bnh=181&tbnw=247&start=0&ndsp=27&tx=127&ty=87 < Link To http://www.google.co.uk/i...7&tx=127&ty=87

 

[GAP]

If you are using old Bachmann sound cards you might want to consider this upgrade.
http://www.girr.org/girr/tips/tips4/bachmann_sound_tips.html
I have used it for putting sound into an LGB tank engine and it sound OK.
I have even built the circuit on veroboard and it is destined for a Stainz
Again like you said they are not the best but I used them because;
1 they were there and,
2 they are cheap and do a reasonable job.

 

[gregh]

First, my rant..... it's a Garratt (two a's, two r's and two t's). garrets are in castles.
OK, chest is clear now.

I doubt you can use Bachmann boards in series - they use the wheel cam to switch the negatives (somehow, never quite mastered how the cct works.)

21 volts !!!!. I bet it flies with that voltage.
To get 9V, Just buy a LM7809 voltage regulator (similar to suggested in post #2). Just has 3 terminals - google the number for pin connections. No other components needed. If you can't get 9V try a 7812 for 12V. They are rated at 1Amp - plenty for two Bachmann units.
Here's the simple connections you need....

The Bachmann unit works OK at 12V - if you go much higher than 12V, the sound gets a bit 'scratchy'.
I agree with GAP that the cct mods recommended in his link are worthwhile. The main problem with Bachmann is when you stop with the wheel switch (cam) closed you have a loud continuous hiss. And with the 2 units in the Garratt, that's almost certain. So I recommend the mod titled " Stopping the Continuous Chuff "

 

[Tony]

Many thanks for the Help and it has all been taken on board especially the Spealin mistake Greg but fitting developments overnight have made me scrap the idea as one Bachmann sound unit in a small loco is okish but two (powered by 9v batteries) is just a total sound mess and so its back to the drawing board, may have to invest in something better (Any suggestions for one authentic sounding analogue sound card that takes two chuff inputs) greatly received

Tony

 

[beavercreek]

Hi Tony
You could go down the route that I did with my Bachmann Annies and use an LGB sound board from the Uintah/Sumpter locos (they are Mallets/Articulated as opposed to Garretts but the sound will be fairly similar).
They are still popping up on German ebay.
http://www.ebay.de/itm/LGB-ERSATZTE...dellbau_Modelleisenbahnen&hash=item53f7016a3a < Link To http://www.ebay.de/itm/LG...mp;hash=item53f7016a3a

OR from Modell-land:
http://www.modell-land-service.de/soundplatine-20882-uintah-usdampflok-69800s313-p-9492.html < Link To http://www.modell-land-se...-69800s313-p-9492.html

Here is the thread for my use of them in the Annie tender. Post 16 has the piccies:
http://www.gscalecentral.net/tm?m=217711&high=annie < Link To http://www.forum.gscalece...=217711&high=annie

 

[bobg]

First, my rant..... it's a Garratt (two a's, two r's and two t's). garrets are in castles.
OK, chest is clear now.

Ahh! But A Garrett (u/c G, two r's, two t's) Is also a traction engine . . . . . . . . . . .

or a Leslie.

 

[gregh]

Ahh! But A Garrett (u/c G, two r's, two t's) Is also a traction engine . . . . . . . . . . .
or a Leslie.

Always learning something on GSC

 

[gregh]

...... but fitting developments overnight have made me scrap the idea as one Bachmann sound unit in a small loco is okish but two (powered by 9v batteries) is just a total sound mess and so its back to the drawing board, may have to invest in something better ......
Tony

That's bad luck. Both my Garratts have dual sound units (not Bachmann) and they sound pretty good. One is driven by cams (Bachmann Big Hauler motor blocks) and the two units drift in and out of synch. Especially good at slow speed.