556s

[jonathand1000]

Hi there,
I'm having real trouble getting a 556 to work properly...I've tried three different actual ICs so faulty components is probably not the problem. My problem is that the two timers seem to affect one another when both No connect, in parallel with the dioderunning in astable mode, even when all pins are connected. In fact, the output seems to change when I connect an output to either output pin. I've set the two astables up as follows: connect a forward biased diode, resistor and capacitor in series.Now connect a resistor and a diode in series, all in parallel with the original diode. (the second diode should end up reverse biased). The wire is connected after the first diode to the threshold and trigger pins, and before that diode to the discharge pin. Could anyone please suggest what I am doing wrong?

Thanks in advance,
Jon

 

[ljcox]

You should have posted a circuit of your arrangement.

I suspect that you have not included a bypass capacitor.

A 100 nF cap across the supply (one per IC or one per 2 ICs) reduces the supply impedance and this prevents coupling between devices.

 

[mozikluv]

556

hi

as what ljcox said a posted circuit diagram would have been better. i agree with ljcox that you might have neglected the 100nf cap on pin 3 and 11.

are you trying to have timer 1 drive timer 2? if so, you should connect an elec. cap from pin 5 (timer1 output) to pin 8 (timer2 trigger).

 

[jonathand1000]

Thanks guys - all working now

Jon