# physics lab help

Discussion in 'Homework Help' started by uaphysics29, Apr 23, 2012.

1. ### uaphysics29 Thread Starter New Member

Apr 23, 2012
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0
I have two circuits to design and I am kind of lost. if anyone would like to help, let me know, my lab is in a couple of days.
Usingonly DC voltage, create a circuit that blinks two LEDs at the same frequency but out of phase by 180° (this means that whenever one LED is lit the other is off and vice versa) without any external manipulations. Although you may have multiple connections to power supplies, the circuit you design must be a single circuit and not simply multiple circuits running in parallel.
Design a circuit such that two LEDs will each light up over their own range of AC input voltages when only the Wavetek output frequency is adjusted. The frequencies that light up the LEDs cannot overlap,so you will only have one LED (if any) blinking (or steady depending on frequency) at any given frequency. Your overall circuit can be composed of smaller circuits running in parallelif you desire.You can decide the range over which each LED lights as well as the constant input voltage signal amplitude you want to use.

2. ### BillO Distinguished Member

Nov 24, 2008
994
139
For the first one look up astable multi-vibrator

For the second one, look up low-pass and high-pass filters.

uaphysics29 likes this.
3. ### WBahn Moderator

Mar 31, 2012
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6,682
It helps a lot if you describe the type of course this is for and what kinds of solutions are "fair game". Otherwise, you might get a lot of hints and suggestions that involve things you haven't gotten to yet or that are not acceptable for this course.

The solutions for a course that is covering 555 timers and digital logic would be very different from one that is covering FPGAs and very different still from one that is all about transistor circuit design.

The suggestions by BillO are a good place to start, provided ASMs are fair game (even if they aren't officially, that's basically what you are going to end up with).

4. ### uaphysics29 Thread Starter New Member

Apr 23, 2012
4
0
its a course on electronics through the physics dept. we've used transistors a few times before and just started with logic gates a couple of classes ago. those guidelines were all that were given, so i'm assuming anything that falls within them should be allowed