Can someone check this Circuit?

  • #1

Main Question or Discussion Point

I got this off of a site and i need someone to check the circuit before i finish buying all the parts (they are REALLY expensive and i cannot salvage right now lol)

--circuit--
http://www.electronicpeasant.com/projects/ledlamps/ledorgan.gif

--project site--
http://www.electronicpeasant.com/projects/ledlamps/ledcolor.html


P.S. on the site it says i can use 2 high output LED's for every 1 that is shown in the schematic...but since i cannot spend too much money, i am going for plain bright LED's....can i still use 2, or will the output not be enough from the amount of current going in?

thank you!
 

Answers and Replies

  • #2
595
0
I don't see where it says what transistors are to be used but most any small TO3 package types are good for at least 100mA. With the 470ohm resistor and 6v power you have (less than) 12mA through the LED. I'd ball-park most LEDs at 20-30mA, so you could probably double up the LEDs and halve the 470 to 220 or such without any trouble. You can (usually) run LEDs of the same type directly in parallel without separate limit resistors, but YMMV so some bread-boarding might be in order.

And for low-price transistors and LEDs, let me again refer you to the two surplus outlets in your previous thread.
 
  • #3
4,261
44
Is this a kind of bar graph of Treble, Middle and Base? The higher the output, the higher it goes? I got this from reading the schematic and I don't see anything particularly flault from a few minutes looking at it.

There are many cheap transistors that is in TO-92 that can do the job( 2N2222, 2N2906, 2N2907 etc.), go to a surplus store and find things really cheap. You can breadboard one chain to test it out. All you have to do is change the coupling cap at the input from 2200pF to 0.1uF to 4.7uF and get the three responds to test out the circuit.
 
  • #4
hey, i got a transistor from a guy who told me it was a 2n4403 npn...which is the same thing as the 2sa1175 npn....but on the back of the transitor:

there is a squiggly symbol (like an approximation equals to sign) and 330...and right below it says 4403....so did he give me the wrong transistor?
 
  • #5
4,261
44
hey, i got a transistor from a guy who told me it was a 2n4403 npn...which is the same thing as the 2sa1175 npn....but on the back of the transitor:

there is a squiggly symbol (like an approximation equals to sign) and 330...and right below it says 4403....so did he give me the wrong transistor?
As long as it say 2N4403, I think it is ok.
 
  • #6
vk6kro
Science Advisor
4,081
40
It looks like the 2N4403 and 2sa1175 are both PNP.
 
Last edited:
  • #7
4,261
44
He need both NPN and PNP. So now he just need to shop for the NPN.
 
  • #9
vk6kro
Science Advisor
4,081
40
Why do the PNP transistors seem to be drawn with their emitters and collectors swapped?
Yes, they seem to be drawn wrongly.

It seems to be an incredibly complex circuit for what it does.
Three LM3914 chips could do the same job at a fraction of the cost.
 
  • #10
Is there something I need to change on the circuit? because I am just about to solder it...

also, while i was building I noticed that the negative end on the capacitor is hooked up to the positive end of the battery...is this ok? I really don't have much experience when it comes to this stuff.

thank you

--edit--
i posted that reply about the transistors incorrectly....the 2n4403 is pnp...the rest are npn
sorry
 
  • #11
1,679
3
Not ok. Your cap must match the battery polarity. Something is backwards.

Carefully check everything before applying power.
 
  • #12
so in the schematic linked above...i just need to switch the polarity of the capacitors? no need for re-evaluating the entire circuit right?
 
  • #13
4,239
1
so in the schematic linked above...i just need to switch the polarity of the capacitors? no need for re-evaluating the entire circuit right?
Not the capacitors, but the two 2SA1165 transistors. more than likely. are hooked up wrong in the schematic.
 

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