Nand Gate oscillator help

[Gryd3]

@IC71 your very welcome!
I take it you don't need that picture

All it takes is a brief oversight or misunderstanding. Even if you understand how it should be connected, the tiniest alteration can make a big difference.

Enjoy playing, and by all means, if you have another questions let us know!

 

[IC71]

Hello again.

I got such awesome help last time..... so I'm back again! I am having another problem with my circuit.

I am on lesson 29: Using Transistors to Amplify the Output of the "Electronic Circuits for the Evil Genius book", and like the title said, I have to use a PNP transistor to amplify the volume of the output of the circuit.

I replaced the LED with a speaker, my 2.2 m resistor with a 22 k resistor, and my 0.1 μF capacitor with a 0.01 μF capacitor.

the book told me to rewire my circuit to include the PNP 3906 transistor. It said that it would make the sound from the speaker louder, but I don't hear any difference in volume. Do I have the transistor plugged in correctly? If not, how does the transistor fit in?

 

[Gryd3]

Yes, it is wired incorrectly

Let me ask you this. On your diagram.
What should the + for your speaker be connected to?
What should the - for your speaker be connected to?

 

[IC71]

Yes, it is wired incorrectly

Let me ask you this. On your diagram.
What should the + for your speaker be connected to?
What should the - for your speaker be connected to?

+ should be connected to leg E and - is connected to.... leg C?.... leg B? I know leg B is connected to pin 10, but the black wire was connected to pin 10 before the PNP... uh... I don't know, the schematic looks like C is connected to Ground? Should the black wire connect to leg C, and do I remove the yellow wire connected to the + wire?

 

[KrisBlueNZ]

One side of the speaker (the red wire) is connected to the emitter of the transistor. That's right. Where should the other side of the speaker be connected to?

Also there is a yellow link wire from the emitter of the transistor to one of the power supply rails. It shouldn't be there.

You may have damaged the transistor. You may have to replace it.

 

[Gryd3]

+ should be connected to leg E and - is connected to.... leg C?.... leg B?

In the diagram, I see the Speaker + being connected to the + power rail.
The Speaker - is connected to leg E. That takes care of the speaker... Just need to doublecheck the transistor.

I know leg B is connected to pin 10, but the black wire was connected to pin 10 before the PNP... uh... I don't know, the schematic looks like C is connected to Ground? Should the black wire connect to leg C, and do I remove the yellow wire connected to the + wire?

leg B should be connected to pin 10 and NOTHING else ;P
leg E should be connected to the - of the speaker and nothing else.
leg C goes right to ground.

This is the important page to me: https://www.electronicspoint.com/attachments/img_2609-jpg.15379/

 

[IC71]

In the diagram, I see the Speaker + being connected to the + power rail.
The Speaker - is connected to leg E. That takes care of the speaker... Just need to doublecheck the transistor.

leg B should be connected to pin 10 and NOTHING else ;P
leg E should be connected to the - of the speaker and nothing else.
leg C goes right to ground.

This is the important page to me: https://www.electronicspoint.com/attachments/img_2609-jpg.15379/

so is this right?

 

[Gryd3]

Looking much better now.
If it does not work, you may need to replace the transistor... hooking it up the way it was before may have damaged it.

What will happen now, is the Nand gate will trigger the transistor. The transistor can handle more power, so the way it's hooked up should allow for a louder speaker.

 

[IC71]

Looking much better now.
If it does not work, you may need to replace the transistor... hooking it up the way it was before may have damaged it.

What will happen now, is the Nand gate will trigger the transistor. The transistor can handle more power, so the way it's hooked up should allow for a louder speaker.

Thank you so much... again! This was really helpful

 

[Gryd3]

Not a problem.
You'll get used to it, You keep over complicating the schematics I think and think what might be connected through other things.

 

[IC71]

Hello again

I had just built a circuit and I am having a very difficult time trying to ID the current problem with it. It is suppose to turn on with the touch switch and get turned off by the other touch switch. Instead, it turns on when I touch the first switch, and then turns of immediately after I let go! I don't know whats happening? I think i have every thing in the right place, and it does not look like the solder is connecting any unwanted wires, I just don't know whats wrong?

 

[KrisBlueNZ]

Can you post the schematic?

 

[IC71]

Can you post the schematic?

Here are the top and bottom schematics

 

[KrisBlueNZ]

Those aren't schematics. The second picture in post #22 is a schematic.

 

[Arouse1973]

Isn't the schematic in post #22? But looks like a switch has been connected instead of R2. What diode is used for D1? and what size capacitor for C1?
Adam

 

[KrisBlueNZ]

Not according to his description of what the circuit is supposed to do, in post #31.

 

[Arouse1973]

Yes, I think he has modified this without telling us

 

[IC71]

Isn't the schematic in post #22? But looks like a switch has been connected instead of R2. What diode is used for D1? and what size capacitor for C1?
Adam

C1 is a 1μF, D1 is a signal diode (skinny gold) and here is my schematic

 

[IC71]

The only modification I made was the touch switches. It worked perfectly on the breadboard, but I started to have the problem after I soldered the parts into the PBC. My electronics teacher just replied to my question saying that the IC, D1, and/or transistor could have been damaged by the heat of the soldering iron.

 

[KrisBlueNZ]

That circuit isn't going to do what you want. If the contacts drawn next to C1 are a touch switch, they won't do anything because that node in the circuit is driven by pin 11 of the IC. The behaviour you'll get is that when you touch the left hand contacts, the oscillator will run, and when you release them, it will stop. C1 will have no effect.

You can get the behaviour you want. I'll post a diagram shortly.