- #1
ToXic_Knight
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Voltage = 9.0 V, Current = 20 mA, Capacitor (C) = 10 microF, Resistance before (too high) [R_A = R_B] = 10 k Ohms.
In a a-stable oscillator, calculating the resistance needed for two resistors (R_A = R_B) to discharge and charge a capacitor (C) so that a LED does not blow. Currently my circuit has much too much resistance for testing and it works with the LED very dimly.
Here is the worksheet: http://i.imgur.com/nx6bnkw.jpg
a-stable oscillator: http://i.imgur.com/xWSC25R.jpg
Relevant equations
I know questions I have to do shortly require a few calculations with the resistance and capacitor, but I need other values first.
t_charge = (R_A + R_B)C sec
The attempt at a solution
I assume V_cc is the input voltage, so that is 9V. I have measured that the amplitude from V_low to V_high is 9V. I thought V_low should be zero, but the diagram has it separate and I don't know whether to follow that or not.
I know that V_D to V_U has amplitude 3V, but I have no idea what the actual values are.
This is probably very wrong, but I could assume that the distance between zero and V_D and V_CC is 9-3 = 6 V and that each then must be 3 V.
Time to charge is 150 ms, time to discharge is 65 ms.
Summary of measurements: http://puu.sh/hvONo/851b30c03f.png
I'll keep editing this post as I work on it, but I've been stuck for days without making much progress.
Other questions:
Reading the questions ahead, I don't feel very confident with them either, so some tips or telling me what equations/variables to use would be very helpful.
Scary questions: http://i.imgur.com/Mf6iBij.jpg
http://i.imgur.com/2jSn6A9.jpg
http://i.imgur.com/0S8WBj8.jpg
In a a-stable oscillator, calculating the resistance needed for two resistors (R_A = R_B) to discharge and charge a capacitor (C) so that a LED does not blow. Currently my circuit has much too much resistance for testing and it works with the LED very dimly.
Here is the worksheet: http://i.imgur.com/nx6bnkw.jpg
a-stable oscillator: http://i.imgur.com/xWSC25R.jpg
Relevant equations
I know questions I have to do shortly require a few calculations with the resistance and capacitor, but I need other values first.
t_charge = (R_A + R_B)C sec
The attempt at a solution
I assume V_cc is the input voltage, so that is 9V. I have measured that the amplitude from V_low to V_high is 9V. I thought V_low should be zero, but the diagram has it separate and I don't know whether to follow that or not.
I know that V_D to V_U has amplitude 3V, but I have no idea what the actual values are.
This is probably very wrong, but I could assume that the distance between zero and V_D and V_CC is 9-3 = 6 V and that each then must be 3 V.
Time to charge is 150 ms, time to discharge is 65 ms.
Summary of measurements: http://puu.sh/hvONo/851b30c03f.png
I'll keep editing this post as I work on it, but I've been stuck for days without making much progress.
Other questions:
Reading the questions ahead, I don't feel very confident with them either, so some tips or telling me what equations/variables to use would be very helpful.
Scary questions: http://i.imgur.com/Mf6iBij.jpg
http://i.imgur.com/2jSn6A9.jpg
http://i.imgur.com/0S8WBj8.jpg
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