Why doesn't this work? (transistor pin identifier)

[carbonzit]

Can anyone tell me if this circuit will or won't work as shown?

I built this without the bilateral switches (so lose IC2, R7-R10). I get no action out of this.

I used a 74LS00 quad NAND instead of a 4011, but that should still work, right?

Any help appreciated.

 

[crutschow]

Can anyone tell me if this circuit will or won't work as shown?

I built this without the bilateral switches (so lose IC2, R7-R10). I get no action out of this.

I used a 74LS00 quad NAND instead of a 4011, but that should still work, right?

Wrong.

Why do people build circuits with substitute parts without reading the data sheets and then wonder why they don't work?

The input characteristics of a 74LS00 and the 4011 are quite different, which the data sheets will show you. The 74LS00 is a TTL device which requires 0.4mA to ground for a logic low. That requires a lower impedance than 10kΩ. The 4011 is a CMOS device and requires <1µA for a logic low. 10kΩ is fine for that.

 

[DerStrom8]

The most likely reason I can think of is that you have the wrong type of transistor. This circuit (I think) is for NPN. You might have a PNP.
Totally a shot in the dark on my part...
Good luck anyway!
Der Strom

EDIT: Just saw crutschow's answer--it is probably the right one

 

[carbonzit]

Yes--the circuit is supposed to work on both PNP & NPN, as it identifies the polarity as well as the pin functions.

So, @crutschow: Are you saying a 74LS00x will work with a smaller resistance, or should I just get the 4011 and not bother trying to substitute?

 

[crutschow]

I recommend using the specified 4011 parts. You would have to change both the resistor and capacitor values otherwise.

 

[audioguru]

Post a video of the old TTL IC blowing up when it is powered by 9V. It is made for 5V.

 

[carbonzit]

Not to worry your pretty little head about it. Actually, the datasheet says absolute max Vcc is 7 volts.

If it makes you any happier, I did blow up a transistor (2N3904) the other day. Pretty spectacular for a li'l jelly-bean part, actually: made a pretty good POP!

 

[colin55]

I have a very simple circuit of the same design, using a 74c14, if you want it.

 

[carbonzit]

Sure, why not? Please post it. Of course, this circuit is also very simple; just doesn't work with the chip I have. I guess I'll have to spend another 69 cents ...

 

[colin55]

TRANSISTOR TESTER COMBO-2
This circuit uses an IC but it has been placed in this eBook as it is a transistor tester.
The circuit uses a single IC to perform 3 tests:
Test 1: Place the transistor in any orientation into the three terminals of circuit 1 (below, left) and a red LED will detect the base of a PNP transistor an a green LED will indicate the base of an NPN transistor.
Test 2: You now now the base lead and the type of transistor. Place the transistor in Test 2 circuit (top circuit) and when you have fitted the collector and emitter leads correctly (maybe have to swap leads), the red or green LED will come on to prove you have fitted the transistor correctly.
Test 3: The transistor can now be fitted in the GAIN SECTION. Select PNP or NPN and turn the pot until the LED illuminates. The value of gain is marked on the PCB that comes with the kit. The kit has ezy clips that clip onto the leads of the transistor to make it easy to use the project.
The project also has a probe at one end of the board that produces a square wave - suitable for all sorts of audio testing and some digital testing.
Project cost: $22.00 from Talking Electronics.
**broken link removed**