Beginner needs assistance analyzing electr. system

[haqpod]

Hello, I have recently begun assembling the prototype of the robot instructed in "Robot Building for Beginners" by David Cook on a breadboard. Problem is I have run into a brick wall. When I installed the comparator circuit and powered the system up I lost electrical power on the system: the indicator light lights up and then quickly fades, while the voltage begins dropping to zero. I know nothings wrong with my battery. It's like the circuit short circuited, but I can't locate the problem.

Here is my system. I know it's messy, but I just started this hobby a few days ago.



I hope some of you are able to help me point out the problem. The red cable coming out of the battery is the positive pol.

- Haqpod

[SmAsH]

do you have access to a multimeter? that is generally the easiest way to locate a short...
i cant seem to see the image, can you try uploading it from your pc?
that way i can see what is going on...

[haqpod]

Uploaded the picture: http://www.megaupload.com/?d=4OKTR7JT

[Soeren]

Hi,

Not knowing the schematic you build after, I can only point you to the most obvious mistakes.
The voltage regulator (i assume) in the right side of the picture doesn't seem to have a ground reference (but who knows what lurks in the shadows).
The LDR bridge seems to be driven from the outputs of the dual op-amp/comparator used (I guess the 1.1k resistors should have been in the vertical strips where you connected the inputs to the IC).

For more answers, please provide the schematic, instead of a somewhat unreadable picture.
Write down the component values as well (we're good, but we're not oracles ).
In your pic, it's next to impossible to follow the circuit and there's no reason to - you want help, so start by helping yourself by posting hard facts, not soft (focused) photos.


I do wonder why there's a voltage regulator in that circuit, as there's no need for it - sloppy design I guess.

[Admin]

Yea, multimeter everything:
http://www.societyofrobots.com/robot_faq.shtml#circuit_debug

I do wonder why there's a voltage regulator in that circuit, as there's no need for it - sloppy design I guess.

I'm sure you made mistakes back in your early days, too
Its sometimes hard to remember that this stuff was once difficult for us back in our early days, no?

[Conscripted]

It sounds like maybe you are charging a capacitor. When it first starts to charge you have voltage and your light but once it gets full it no longer conducts. Just a guess. Which circuit are you working on? (page number)