Quote:
Originally Posted by dougy83  He is more clever than me for assuming that; I didn't mean to state the obvious. |
Maybe I didn't understand that, but who is more clever than you?
I didn't assume that Netguru was going to put the diodes there, I didn't realized what you did about the HIGH in one output was going to turn ON the two LEDs.
Quote:
Originally Posted by dougy83 a pull-up usually pulls an input high; a pull-down usually pulls an input low. It keeps the input in a defined state when it's not being driven by another source. The 10k resistor inline with the switch in your circuit does nothing until the switch is turned on. |
Yes itdoes not do nothing, but the CLOCK will be low anyway, because closing the switch will give a HIGH level, coming from Vcc 'cause the transistor is cut-off, by the way, when you have an open collector in a gate, for example, you need a pull up resistor, not to pull the output high but to complete the arrangement of the internal transistor, that thing over there with the BJT is a NOT gate, if the 10K resistor wasn't there would be happening the same that if you had a NOT with open collector and you don't use the pull up resistor, so as I see it that's a pull up, I agree with you that's not a pull down, but do you think it needs it?
1st November 2009, 10:45 AM
Similar 
Linear Mode
