MIL Elim Circuit Question

[scrupul0us]

JUst a quick question regard the polarity of the CAP in the circuit... am i correct here?

http://newcougar.org/forums/attachment.php?attachmentid=25234&stc=1&d=1150982907

[LinkMan]

You can't tell from the circuit fragment you've posted. :shrug:

It's only a small 1 microFarad cap, get a ceramic or mica cap and use that. A simple ceramic disc capacitor from Radio Shack. Ceramic or mica caps do not have a polarity, so it won't matter. :)

I did some searching, and one wire is the sensor output, and the other wire is the reference voltage from the computer, so offhand I'd have no idea which would be considered "+".

[scrupul0us]

Original Pic:
http://atomicinternet.homeip.net/teamneco/howtoimages/scem.gif

I know what goes into it.. I already have the parts, but I just wanted to clarify the hookup b4 I got it all installed and closed up... My guess is I'm correct... from what I remember from DC electronics, you'd want the resistor b4 the CAP... Maybe ron can chime in

[LinkMan]

It's not a DC circuit.

I'll let someone else chime in on the polarity though, sorry to bother you.

[scrupul0us]

your not a bother at all... i value just about everyones input

[scrupul0us]

FYI this is the CAP I bought

http://www.radioshack.com/product/index.jsp?productId=2062392&cp=2032058.2032230.2032267&allCount=101&fbn=Type%2FElectrolytic+Capacitors&f=PAD%2FProduct+Type%2FElectrolytic+Capacitors&fbc=1&parentPage=family

[scrupul0us]

i msg'd demonsvt since he wrote a thing up.. but havent heard back... bump

[LinkMan]

Googled a little more to find a schematic, it's essentially a low pass filter being used as an integrator, the source voltage is the O2 sensor, the output voltage is to left in your schematic which is the computer's reading. So I believe that your assumption is correct, and the positive + terminal of the cap is topmost near the resistor in the schematic. The tantalum capacitor you have does have a polarity but you should be good with the way you've got it marked.

It's been a long time since circuits class...

[scrupul0us]

i might just goto rad shack today and return the onesi got for these:

http://rsk.imageg.net/graphics/product_images/pRS1C-2160287t98.jpg


1.0µF 50V 20% Axial-Lead Non-Polarized Elect. Capacitor

[LinkMan]

1.0µF 50V 20% Axial-Lead Non-Polarized Elect. Capacitor
Ha! Non-polarized :thumbsup: Good luck, and when you get it put together, throw together a nice FAQ like the SVT Lite upgrade you did.

[scrupul0us]

i just got a PM from demonSVT... i was correct with my polarity guess :)

as for a faq... it should be pretty simple... do you need them? if u said yes build these :)

[LinkMan]

i was correct with my polarity guess :)
Excellent, I guess I remembered something, eventually, from circuits class :rolleyes:

Hey, yeah, make a FAQ. If you had questions about polarity, so will someone else, and now you've got it worked out. :)

[Excelcier]

Woah, missed this thread earlier. Yeah, you MUST use the Tantalum cap, non NP or Electrolytic.

Yes, the cap goes before the resistor. The circuit couldn't possibly be any simpler or easy to build. Just follow the directions EXACTLY.

I coincidentally just added this to my parts bin of things I build and sell now!

http://excelcier.com/market/me

[Tygerr]

Yeah, you MUST use the Tantalum cap, non NP or Electrolytic.

Why?

[Excelcier]

The electrical properties of each type of capacitor do different things.

[scrupul0us]

the parts number is def wrong on that diagram... i got a NP one with a diff part number and i havent had an issue yet...

Ron... way to vacation under a rock :)

[Excelcier]

Yeah, I've been super busy lately building headlight flasher circuits, MIL Elims and LED flasher circuits getting ready for Cougarfest.

I just double checked that schematic link above and the Radio Shack part numbers are perfect. I've built them in the past using that exact drawing / part numbers and they match exactly.

[LinkMan]

Are you using Tantalum because of it's temperature properties? It's been awhile since I've done anything with discrete or analog, so just curious...

[Excelcier]

Yeah, good memory. Basically, the reason for the tantalum in this application is because of its speed and temp properties. Using another one may work for a while but it could breakdown and malfunction earlier.

Here's a great bible link I use for determining what type to use in different applications;

http://www.rohm.com/en/cap/cap_what3.html