k-27 Sierra Sound 9 Volt batt

[bob kaplan]

According to the Bachmann reference:  "When used for DC operation, the track voltage at slow speeds is insufficient to power the sound board.  For best effeccts in slow speed DC operation , a 9 volt battery backup should be added to the Sierra Sound board as per their instructions."  Obviously i know little  by asking this question...but here goes:  i thought th battery from Sierra was 6 volts.  Where do we get the compatable 9 volt battery?  i have only installed one Sierra unit and that was a very long time ago.   So please, excuse the ignorance.
   Thanks for the help.
bob

[Hunt]

Hmm...While it may not be the case in this instance, Bachmann is infamous for typos in their information. Thus, I suggest you ask the folks at SoundTraxx to review and comment on the documentation calling for a 9-volt battery. Provide SoundTraxx with the PDF link
http://www.bachmanntrains.com/home-usa/k-27/installdocuments/Sierra_DC_Sound.pdf

[bob kaplan]

Thanks for the suggestion.   i gave it a try a couple of days ago.  So far no reply from Sierra.   i will let you know if i do get a response.
  bob

[Greg Elmassian]

The soundtraxx documentation calls for a 6v battery. I think the 9v is a misprint or mistake.

In the Sierra literature, they also show feeding the battery terminals with a voltage regulator. They do not show the output voltage from the LM317 regulator, but the output voltage can be closely approximated from Vout=1.25 * (1+(R2/R1)). Sierra shows the 2 resistors as having vales of 220 and 1,000 ohms. thus about 6.93 volts.

I would use the recommended voltage from Sierra.

Regards, Greg

[Tony Walsham]

I could of course be wrong but as I understand it the 9 volt battery was wired into the Bachmann circuitry as a method of keeping the Bachmann electronics " alive" at very low or no speeds.

[bob kaplan]

Thanks for the replies gentlemen.  But one seems to be in contradict the other.  Knowing nothing of electronics, i need something a bit more definitive.  Sierra has not yet replied to my e-mail; but if they do i will post what information they give me.
  Again, thanks.
bob

[Greg Elmassian]

Reading the instructions from the link you provided... the sierra "backup" battery is correctly identified the first time in the document as 6v.

Later in the document, it is referred as the Sierra backup battery again, but 9 volts.

The chuff circuitry does not need 9 volts, even though it is not referenced, only the Sierra backup. The battery is not indicated as connected to the chuff circuitry.

I'd stick with the 6 volts as sierra calls for and the document calls for correctly the first time.

Tony, try re-reading that document and see if I missed something.

Regards, Greg

[StanAmes]

Greg is correct, the second reference to 9 volts is a typo.  If you look at the photo at the bottom of the page you will see the standard Sierra Battery.

Stan

[bob kaplan]

Thanks for the help.  It is appreciated.
bob