Joe, Thank you for the response and info. I'm very familiar with the Midcom transformer and inductor products. Midcom has inductors for billing-tone filters, but they have too much height to mount on component side of PCB and allow the PCMCIA cover to be installed. To use the Midcom inductors requires routing a hole in the PCB so inductor can be suspended (on its leads) in the hole. PCB area is at a premium. As a consequence we cannot afford to lose PCB area on the bottom side due to routing.
What we really need is a 1.8 mH inductor that will mount on the comp side, with a maximum height of 2.5 mm. The circuit requires a minimum of 1.8 mH to insure the first order filter has enough attenuation at 12 KHz. I don't have the area to add a second inductor for additional filtering. To use a one-inductor-first-order-filter, the inductor Q needs to be a minimum of 30. We may have to use drastic measures and rewrite the laws of physics to find an inductor that will do the job. Regards, Duane On Sat, 4 May 1996, Jon D Curtis wrote: > > From: Joe Dwyer/Inter-Tel <joe_dwyer%[email protected]> > > Date: 3 May 96 16:53:40 MS > > Subject: Re: Inductors for Billing-Tone Immunity > > Mime-Version: 1.0 > > Content-Type: Text/Plain > > > > Give Bob Reiter at Midcom a call > > 1 800 643-2661 or 605 882-0353 > > fax 605 886-4486 > > > > I recently saw some transformers that were PCMCIA that I couldn't believe > > how > > small they were. They also have an inductor line, so maybe they can help. > > > > I have also done a BTF for Swiss so let me know if you need help with > > values. > > > > ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> > > > > > Joe Dwyer > > Sr. Engineer International Approvals > > Inter-Tel. Tel: +1 602 > > 961 > > 9000 x1235 > > 7300 West Boston Street Fax: +1 602 961 1370 > > Chandler, AZ 85226 U.S.A. > > Internet: [email protected] www.inter-tel.com > > Inter-Tel designs and sells PBX and Hybrid Telephone equipment worldwide. > > ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> > > > > To: treg @ world.std.com @ SMTP > > cc: > > From: dmarc @ crl.com (Duane J Marcroft) @ SMTP > > Date: 05/03/96 01:11:21 PM > > Subject: Inductors for Billing-Tone Immunity > > > > Hi TREG'er, > > > > I'm designing a V.34 on a PCMCIA card for Switzerland. Does anyone have a > > source of Metering-Tone or Billing-Tone inductors that are less than 2.5 > > mm in height (max height above PCB) and will sustain up to 60 mA of line > > current before saturating. Any information would greatly appreciated > > > > Thank you in advance. > > > > Regards, > > Duane Marcroft > > > > > > > > >
