hi,
You are operating the 4013 at 5V, right click on the 4013 symbol and then edit the Spice line from VDD=5 to VDD=9. the LED current will be higher. OK
EDIT:
You are showing a Diode symbol for the LED. Use key F2 , select the LED symbol, then right click the LED symbol and then choose the correct LED from the displayed list.
ok silly mistake by me.
now current is comming 7.5mA acrross R3 , does LED also have resistance which is to be considered ?
Also when i change value of R3 voltage value at Q output pin changes.
it decreases with decreasing resistance value.
when R=10ohms Q=6.8V
when R=100ohms Q=8.8V
when R=1000ohms Q=9V
ok silly mistake by me.
now current is comming 7.5mA acrross R3 , does LED also have resistance which is to be considered ?
Also when i change value of R3 voltage value at Q output pin changes.
it decreases with decreasing resistance value.
when R=10ohms Q=6.8V
when R=100ohms Q=8.8V
when R=1000ohms Q=9V
hi,
You are still using a diode as an LED, that diode has only a forward voltage drop of 0.7V, use a RED LED, which is ~2V forward drop. [your current results will be misleading with a diode]
The falling voltage, when the current load is increased, is the point I was making yesterday in your 4013 thread, you will not get 15mA at 15V.
hi,
You are still using a diode as an LED, that diode has only a forward voltage drop of 0.7V, use a RED LED, which is ~2V forward drop. [your current results will be misleading with a diode]
so what this has got to do with falling voltage. the load is controlling voltage drop accross Q and gnd ? , what if i connect many transistors with load like that in parallel or sereis with output Q, then load will change and it will change all voltage drop accross output !
this is not typical characterstics of driver circuitry !
hi,
If it was important to keep the Q output at its highest output voltage, I try to keep the load current to less than 5mA.
This is easily done by using a transistor as a driver for an external LED's in the way you have shown it.