choke

[tvman]

i checked the shelves at the shack and couldn't find none.
so i need instructions on how to wind a couple of 1uh choke for my project.i suspect i'll need to wind the wire on a high value resistor. so what gauge and how many turns do i need?

barry

[bobsRAC]

Have you checked digikey.com, mouser.com, bgmicro.com?

[Edd]

Barry...Mr TV man :
I'm assuming U to have some old hi value carbon composition 1/2W res avail for coil forms.
So take one and file a groove/notch on each end to channel your wire up onto the "coil form" then find some 24 or 26 ga wire(pretty pop size for TV inductors) and strip one end and solder to one res wire lead and then put on 27 turns, close wound filling in a 10 mm width on the res form or spaced out to fill 10 mm width if U use
the smaller ga wire . Strip wires end and wrap around the res other lead.......done .....1uh.
Takes quite a few more turns on an air wound core than when U're using a magnetic core! <p>73's de Edd
[email protected]
(Interstellar~~~~Warp~~~~Speed) <p>[email protected]
(Firewalled-Spam*Cookies*Crumbs) <p> <p>[ August 27, 2002: Message edited by: Edd Whatley ]</p>

[tvman]

thanks ED
exactly what i was looking for. and i have a few high resistance,half watt carbon comp res left over from the old days.
barry

[Dean Huster]

Just don't forget that the resistor will be in parallel with the choke and the lower the value, the lower the Q of the choke. If you consider 10K to be a high value, you may be too low. Even though it may be an overkill, try to get one of those old resistors up above 10M ohms if you can just to make sure. Heck, unless you work with hi-Z FET or vacuum tube circuits, you won't be using those multi-megohm resistors for anything else anyway!<p>Dean

[tvman]

even in my retirement i repair an old modular zenith syst 3 now and then. one of the resisters that frequently goes bad(it opens)is a 2.7meg 1/2 watter.
using this i wont worry about lowering the coils Q.

the project i'm building is the "blab buster" that was in the feb issue of N&V. the choke is on one of the 2 Vcc lines to the chip. i think anything i wind thats somewhere in the ball park will work ok. its not like i'm using the choke in an osc ciruit where the value is critical.

[MrAl]

Hi there,<p>Do you know what the value (uH) is suppose to
be?<p>--Al

[tvman]

mr al
the same 1 uh as in my first post :&gt .
barry