OK, I have no idea what I'm doing; but would greatly appreciate your
help! but I decided I wanted to build my own circuit. Its a Low Voltage
Battery Disconnect. Heres the schematics, and I tried gathering all the
parts I needed using alliedelec.com... but I am unsure on a few. (see after
pictures)

Not exactly which part for theeese.

U2: 78L05, 78M05, or 7805 5 Volt regulator
I have no idea.
http://www.alliedelec.com/Search/SearchResults.aspx?Ntt=78M05&N=0&Ns=Popularity%7c1&i=&Ntk=Secondary
http://www.alliedelec.com/Search/SearchResults.aspx?Ntt=78L05&Ns=Popularity%7c1&i=&N=0&Ntk=Secondary


D1-D6: 1N4148 switching diode
I see they range from 100-500mA, different voltages.
http://www.alliedelec.com/Search/SearchResults.aspx?N=0&Ntk=Primary&Ntt=1N4148

　
C1: 0.001 mF ceramic disk capacitor
50 or 100 vdc? They all seem to be the same :/
http://www.alliedelec.com/Actives-and-Passives/Capacitors/?N=4294821930+4294840716+4294827505


C2-C6: 0.01 mF ceramic disk capacitor
what voltage rating? 16vdc is my guess here... but not exactly sure.
http://www.alliedelec.com/Actives-and-Passives/Capacitors/?N=4294821930+4294840716+4294855885


C7-C10: 0.1 mF ceramic disk capacitor
16vdc aswell?
http://www.alliedelec.com/Actives-and-Passives/Capacitors/?N=4294821930+4294840716+4294924622


C11: 22 mF, 16 V electrolytic capacitor How many Ohms?
http://www.alliedelec.com/Actives-and-Passives/Capacitors/?N=4294821930+4294821309+4294839100+4294827693+4294924977


VR1: 100K trimmer pot, 10 turn variety preferred
A lot of results, Just get one 10 turn? Would I have more precise measurements with say, a 25 turn? If thats the case, I would opt out for that instead.
http://www.alliedelec.com/Search/SearchResults.aspx?Ntt=100K+trimmer&N=4294966088&Ntk=Primary
　
　


I'm fairly certain these ones below are what I need.
　
U1: 1458 dual op-amp
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2880379&MPN=LM1458N%2fNOPB
Q1: IRFZ34
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2731410&MPN=IRFZ34NPBF
D7: 1N4001 1 A diode
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2660001&MPN=1N4001
F1: Automotive fuse (see text)
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=798SPEC&MPN=0001.1014
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=7980586&MPN=0031.3571
S1: DPDT toggle switch
http://www.alliedelec.com/Search/SearchResults.aspx?N=0&Ntk=Primary&Ntt=DPDT+toggle+switch
R1-R4: 100k 1/4 W resistor
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2964745&MPN=OK1045E
R5,R7: 1M 1/4 W resistor
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2966331&MPN=OK1055E
R6: 1K 1/4 W resistor
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2964741&MPN=OK1025E
R8: 22 ohm 1/4 W resistor
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2966568&MPN=OK2205E

 

U2 - does not matter about package. Get the 7805, as it is more robust.

D1-D6 - a 1N4148 is a 1N4148. Don't worry about anything but a leaded package (probably DO-25).

Ceramic disks - 50 volts is plenty. Worry about lead spacing (.100 or .200).

C11 - electrolytics have no resistance rating. Get 22 uF @ 16 volts. You only need be concerned about the package - axial or radial leads.

VR1 - You're correct, a trimmer will always have more then 10 turns. And the 25 turns will allow better resolution.

The parts need to be selected with an eye towards construction of the circuit. If you are doing it on a PCB, then surface mount components could be used. Otherwise, leaded components are much easier to handle.

 

Ahhhh! so they are all essentially the same thing fuction wise; just different shapes and sizes. Don't know why I didn't think of that. I was searching for all the parts and reading how they all worked on wikipedia... I got overloaded with information I guess.


Step 2... learn free pcb or a similar program!

thanks again.

 

About the CAD program - you have to have the parts preselected so things like pad sizes and spacings are correct. If the part is not in the CAD program's parts library, you can get the engineering drawings from the manufacturer so you can make an exact part to enter into the component library.

It feels uphill at first, but you do get there.

 

Yup, It would most likely be double work drawing it up on the computer and then sorting out which parts I want to get...

this is one of the more harder projects I have done... But certainly not the first time I dive headfirst into something I have no knowledge of. Its a fun experience. I dont know, maybe I'm just weird. haha.