Gameshow Buzzer questions

[CeaSaR]

Hello everyone,<p> I have been recruited to build a gameshow buzzer for my children's school. Thank goodness for TJ Byers Q&A column. I have decided to use the circuit that James Drake submitted in the Nov. 2003 issue on page 30. I like the idea of using SCR's instead of relays, but my local RatShack doesn't carry them anymore. They don't even list them on-line!
I went to Alltronics and found everything I need to build the buzzer, but I have a couple of questions.<p>1.) Can I use a 12v switching power supply for this project? It's hard to pass up a PS for $3.75.<p>2.) The SCR I selected is a 2N5064. Will this particular component work? If so, would there be any changes needed to the circuit?<p>3.) What would be a good value to start with to obtain 6V at the SCR (across the lamp - a GE# BRX6V 6 volt 6W exciter lamp)?<p>4.) I plan on using a piezo sounding unit - Murata # PKM25-6A0. Three terminal, self-excited encased piezo element. Will this unit survive 12V?<p> Thanks for all your help.<p>CeaSaR

[russlk]

Answers to your questions:
1. yes
2. no, 2n54-- is rated at 800 mA, lamp draws 1 amp. Use Teccor #TCR22-4.
3. Use two lamps in series to operate on 12 volts.
4. Yes, buzzer works from 3 V to 15 V.

[CeaSaR]

Thanks Russ! <p>Alltronics list very little spec info on most components (at least what I was looking for). To keep parts count down (and cost), I'll look for a 12v 1/2amp max lamp. <p>Once again, thank you for your concise reply Russ.<p>CeaSaR

[CeaSaR]

Ok, in my sleep deprived state, I couldn't remember how much info Alltronics provided, but after a revist they provide info enough for you to make a fairly informed decision. Sorry Alltronics.<p>CeaSaR