I fried my first chip....maybe chips....

[Bentov]

I was attempting something that I don't even know is possible. Trying to use a 74hct4020(ripple counter) to count up the output from a 556, then use a 10bar led to display the number of pulses. I saw smoke from the 556 , don't know if the other one is blown or not. I guess I have two questions. Could someone point me to a circuit that can test the 4020. I already tested the 556, it's blown. Also, is it even possible to do what I tried to do? I guess I'm trying to do to much to fast....

Bentov

 

[bogdanfirst]

can you post the schematic you used when you blowed the 556? maybe you got the wiring wrong?

 

[Bentov]

Oh, I'm sure I got it wrong. I don't remember all of it, becuase after seeing the smoke, I (I'm stupid) started pulling the connections to the 4020. I'm a real newbie, just trying to make some things from the parts I have. To be honest I was just guessing on how to hook up the 4020 based off of the data sheet....Live and learn I guess. I had the CP hooked up to one of the outputs of the 556( that 556 part of the circuit was correct, it worked before I started messing with it). The MR hooked to groud, q0 to the first bar,q10 to the second bar, and then one I don't remember. I knew I should have written it down. I was just excited that I was able to get the leds to blink. I have a 12v 1.75amp powersupply. both IC were rated above 12v, I'm assuming something I hooked up just pulled to much current; although, I've used a multi meter up to some circuits and I get reading sometimes above 15v...

Hope this helps
Bentov

 

[mechie]

Pop goes the breadboard !

I suppose if your 556 was working before the addition of the 74LS4020 then something at this point of your development went wrong ...

You did put a resistor in series with each LED didn't you ?

Is it possible you reversed the power leads on that last test ?

 

[Bentov]

Yes, my 556 was working before the 4020. I did have a resistor before the single LEDs, but now that I think about it, I didn't have any between the outputs of the 4020 and the led bar(idiotic I suppose) I know I didn't reverse the power leads to the circuit board, but it is possible that I had reversed them to the 4020. I was not understanding how to make the Master Reset not reset until it counted up all of the way, but when I connected it to anything other than ground, the LED bar was to dim and still didn't make them light up any differently. I must have connected it wrong after the LEDs were dimmed...


:?: does anyone have a simple circuit that I could use to test the 4020? Or tell me if CP it connected to the output of the 556, then is MR connected to one of the outputs of the 4020?

Bentov