RE: help needed with simple circuits

["Timothy Morris" <timothy.morris@xxxxxxx>]

Thanks Keith. These guys are all thirteen and they are taking the exams to decide which *REALLY* expensive schools their parents are going to have to cough up for next year :) I can just about remember most of the Chemistry and Physics from 20 or so years ago, biology was my worst science subject (I only managed a 'B' grade). Sometimes I have to ask for help :) It was the LDR that threw me, I found a voltage divider circuit on the web, but I think that is a little advanced for them....

 

 

The "turn over" instruction was a trick question designed to sort the men from the boys....

Tim.

-----Original Message-----
From: Keith Doxey [mailto:ukha@xxxxxxx]
Sent: 02 June 2001 20:11
To: ukha_d@xxxxxxxSubject: RE: [ukha_d] help needed with simple circuits

a  Main ON/OFF switch

b  Limit the current through the LED

c  So the buzzer is silent at night

 

d Cant draw so ....

 

    Replace switch 2 with LDR.

    LDR has low resistance when light shines on it so buzzer would operate

    LDR has very high resistance when dark so buzzer does not sound.

 

did I pass ?

 

Didnt do electronics at school.....the stuff they did in the CSE coursework I had done whan I was 6 or 7 :-))

 

Being a school in a Rural area they did lots of farming/biology stuff. Have to say I dont like cutting up Worms/Frogs etc and on more than one occasion came very close to spilling my lunch on the benches in the science lab :-((

 

Keith  aka the squeamish one !!

 

PS. I turned the paper over as oper the instruction at the bottom but the other side was blank, does this mean

 

a There was only one side of information

b I only have a single sided printer

c I'm stupid

d All of the above

 

:-)

 

 

 

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