Help debugging

[fiveten]

I am having a problem with my transistor switch. I am using a Vcc from a hard drive signal to activate the transistor. When the circuit is powered without the HD signal attached the leds are on but dim. When I connect the HD wire the circuit turns on fully, even when the HD is not active. Can someone give me their technical advise....

p.s. I tried switching the transistor so the collector and emitter is oposite of the diagram. I have built a simmilar project but the pnp transistor switched the vdd to the timer only and the 4017 counter always had power. I just want the leds to turn off when not active. My first project one led was always on but the circuit worked.

 

[fiveten]

diagram

 

[fiveten]

Image will not upload. It is a basic 555 setup to switch a decade counter 4017 with pin 3 going to pin 14.
I am using a pnp transistor to power both ics. The hard drive is a vcc signal I am using to trigger the transistor.

Thanks, fiveten

 

[nos_slived]

Make it upload.

Without a schematic, it is nearly impossible to help you, especially because your description isn't very good.

 

[fiveten]

ok

 

[audioguru]

It would be helpful to know what is your supply voltage.
1) Your transistor is upside down. Reverse its emitter and collector then learn about transistor polarity.
2) The 100 ohm base resistor is much too low in value. Depending on which transistor you have used, the very high base current might have destroyed the transistor. Learn Ohm's Law and transistor theory.
3) The 4017 has only one output on at-a-time. Therefore only one current-limiting resistor is needed, not ten resistors. If the supply voltage is 9V or less, a current-limiting resistor isn't even needed since the 4017 limits its output current at low supply voltages. Learn about the 4017.
Sorry.