Troubleshooting 555 Timer Output to 2/3 Vcc

[wolfram74]

I've got a 555 timer wired up like in this picture

and my output is going to 2/3 Vcc instead of Vcc. This is leading to problems as I have hooked into a decade counter down the line which gets the low timer output and it's output shrinks as well. Any ideas on what I should try?

 

[vk6kro]

The output should be taken from pin 3. This should be a square wave which goes within a volt of the supply voltage.

It is normal to get the voltage you did from pins 2 and 6.

 

[wolfram74]

I am taking the output from pin 3, and the output voltage is pretty much maxed out at the voltages at the max voltage on pins 2 and 6, which is about ~3.6, the Vcc is 5 and I think that's interfering with my decade counters.

 

[uart]

Any ideas on what I should try?

Yeah, double check the power supply rails on your decade counter.

 

[Jiggy-Ninja]

Would a pull up resistor work with 555s?

 

[schip666!]

A pull-up would probably not work as the 555 output both pushes and pulls...

Double check your power-supply rails at the chip. Then I would check to see that you don't have a near-short on your pin 3 output signal someplace -- that could cause the output to droop. If you can, disconnect the pin from everything and see what it does. Then try a different 555 chip to see if you've managed to booger up the output driver by accident.

 

[vk6kro]

If you are using TTL counters ( like 7490, 7493, 74192, 74193 ) then this would be normal.

These chips were OK when driving each other, but the input and output voltages were far from ideal.

A "high" was regarded as anything greater than 2.6 volts and an input actually supplied current to the device driving it.

They were also power guzzlers and many of them ran quite hot.