Re: bulb question - 12v/20W vs. 6v/5w

From: Peter Bennett (peterbb_at_nowhere.invalid)
Date: 10/29/04 

Date: Fri, 29 Oct 2004 13:55:08 -0700

On Fri, 29 Oct 2004 14:33:30 -0400, "Mike" <no_spam@comcast.net>
wrote:

>Hi folks,
>
>Just a couple of days before halloween, it's important for your light-up
>pumpkins and displays to work properly. Unfortunately, one of our displays
>blew a bulb the other night and my wife is somewhat upset about it.
>
>So, after going to four stores (two home depots, one lowes, one wal-mart),
>nobody had the replacement build. Home depot had a spot for the original
>(6v/5w), but both stores were out! So, I picked up at lowes today the
>closest match I could find: 12v/20w. Thinking I can just apply some
>resistors in-line with the bulb, I figured I could have this working again.
>
>Here's my assertion:
>
>The original bulb is a MR11 type, 6v, 5W. The power supply output is 6VAC,
>1000ma. How can I make this bulb work? Sorry if this is a naive question.

You can't, really.

A 12 volt bulb will be very dim when run on 6 volts.

You could build a voltage doubler to get enough voltage - however,
since your power source is only good for 6 watts, it still won't run a
20 watt lamp. 

-- 
Peter Bennett VE7CEI 
email: peterbb4 (at) interchange.ubc.ca        
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