STUDENT needs help!!

[mossy]

i'm trying to create a hand clapper system to turn on lights
electret mic,op amp,j/k flip flop,transistor,relay,bulb, in that order
wot ye reckon???any views??

 

[stevez]

Are you enrolled in a formal program of study? If so then is the expectation that you design it yourself? Clearly you've given it some thought - my compliments to you on that. So many students come to this forum and hope for all the work do be done for them.

I'd be willing to be that this project has been done countless times - sound activated switch might be a good thing to google on. If it were my assignment I'd document my thought process in more detail than you've done here (and maybe you've done just that). A block diagram is helpful - mic senses sound, op amp amplifies it, you'll need something to trigger and have adjustable trigger (comparator maybe?), the flip-flop to toggle on or off, and a power handling circuit driven by the flip-flop -possible to open/close a relay. This proves to your instructor that you did some work and you developed the idea. Now you should be able to go back and find or design circuits to handle the functions in the block diagram. I am certain that a skilled electronics designer could accomplish that task with fewer components but you aren't a skilled designer yet.

Good luck.

 

[mossy]

3rd yr electronic engineering project....its all our own baby!
just thinkin i might need a darlington pair aswell...block diagram is good plan thanks....is there any way such a low volatge circuit could be connected to something to drive a large motor??i might be clasping at straws ere

 

[stevez]

You can drive a relay to handle the current of a motor. Features that I might add to improve the reliability of the device:

A. A filter of some description, that would be optimized for the sound(s) you want to trigger it - clap of hands might be distinct enough though certainly within a wide range.

B. Multiple step triggering - clap, clap, as an aid to limit random triggering by background noise.

C. Some kind of automatic gain or sensitivity adjustment control to adjust for increases or decreases in general background noise.

 

[electronist]

that all is fine but there is a simpler way to go around it. All you need is a condenser mic, two transistors that are designed into a bistable multivibrator and a third transistor to drive a relay and its done. Ive done this ckt in hundreds.

 

[mstechca]

Re: STUDENT in help!!

i'm trying to create a hand clapper system to turn on lights ,
electret mic,op amp,j/k flip flop,transistor,relay,bulb, in that order
wot ye reckon???any views??

The above posters forgot to take into consideration that Mossy wants devices listed to come on in order when the system detects claps.

A sound activated switch would be 1/2 the answer, because it can do one device, but not all of them.

Personally, I dont understand why the items should be turned on in any order at all. If I were to do one, I would have everything go on at the same time.

 

[mossy]

No the order doesnt matter i'm just lookin for this project to work the most economical way whichever way it goes!!
from what i see there is numerous ways to build this
any chance we can agree on a design?
sorry if this sounds rude :?:

 

[_3iMaJ]

I actually assigned this last semester when I taught electronics 1 lab. It was a very good project, it also worked very well.

 

[Thunderchild]

I would go at it like this. a microphone. use one op amp to amplify and filter it in a band pass configuration (u put both condensers and resistors as gain components). a second op amp to act as a comparator and therefor a volume adjustment. this will trigger a JK flipflop. the output of the flipflop will run a darlington transistor that can power low power/voltage devices or for more power a relay. do not forget to put a reversed diode on the relay to protect the transistor and make sure it is rould the right way (reversed so as to protect the transistor from back emf). the realy can power anything up to mains 240 volts and 10/16 amps depending on the relay. if you want to clap more than once the with two or more FF to form a counter/frequency devider u can make it count the claps until turn off or turn on. only draw bak is if say u have to clap 4 times and u clap 3 the one clap will activate it later as it will remember the first three so perhaps then a background noise will set it off and it could be frustrating if all claps are not "caught" as u may end up clapping away.
well how does that sound frofessor ? considering I've never actually made one of these things :wink: