Design

6v & 90v DC Power supply
I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 v... 16 Jan 2006 02:08

Unusual functions of cheap parts
Hi all - After my first thread going from "standard" cheap parts for up to vhf frequency to a discussion about the usefulness of Spice simulator...... I try it another time hopefully get attention of frustrated co-readers: For example the rechtifier diode 1N4007 can be used as a rf switching diode, for example... 26 Jan 2006 02:13

Op Amp Calculations
A lot of years ago (38 to be exact) a wise old "rule of thumb" engineer taught me a slick way of getting maximum gain out of an opamp without resorting to very high or very low values of resistors. As we all know, for an inverting opamp, the gain is given simply by Rf/Ri, where Rf is the feedback resistor from ou... 30 Oct 2005 22:26

Ferrite bar antenna for car radio?
Any idea the best way to couple a ferrite loopstick antenna to a car radio input for AM reception? I experimeted using a 6 inch loopstick (230uH) and 365pF parallel tunning cap from antenna input to ground (chassis) with reasonable results, but I'm wondering what the best approach is. The tuning is very broad... 26 Sep 2005 23:56

Single Op-Amp Current Amplifier
I've been revisiting my op-amp theory, and note that there are cicuits for voltage-voltage amplifiers (non-inverting ), current-voltage amplifiers ( see-saw or inverting amplifier ), but that it's a little more obscure with voltage-current and current-current amplifiers. I've managed to derive the last two con... 10 Sep 2005 12:24

NE602 Primer article?
Has anyone seen a Web copy of the article "NE602 Primer"- by Carr featured in Elektor Electronics Jan. '92 Im interested to get the article. Ive looked at the Elektor site, but their back issues dont go back that far. regards, JEFF ZL3JK New Zealand jeff_164(a)NOSPAMhotmail.com (remove the NOSPAM) ... 3 Sep 2005 08:51

Polymer LED display issue
Hi, I have an application that just suits a Polymer LED display perfectly. I can get a 2 line 16 char display (such as a Delta PDC1602M), and all looks good (power consumption, life, interface etc) The only problem is that buried in the specs is the line that says "Do not hold the same display picture over 1 ... 28 Aug 2005 18:16

Veroboard cutting and veroboard-layouting
Greetings As a newcomer to the wonderful world of electronics, I have recently setup a minor electronics lab in my home and started to build a few things. My tools and equipment exists of standard components (resistors, capacitors, ICs, etc), soldering iron, a bunch of veroboards and a multimeter. I do not, ... 18 Mar 2005 01:49

::: Interfacing Stepper Motor :::
hai all This is balaji & vijay from India. we are doing a Project using Stepper Motor. we need to interface Stepper motor and Intel 8051 using ULN 2003 IC. Can Anybody suggest us some weblinks regarding the same. Thanx in Advance Vijay & balaji Note: If u wish to contact us thru mail ,the mail Id is " vi... 9 Mar 2005 17:24

Impedance of complanar traces on PCB surface?
Hello: I want to lay out a couple of traces on the FR4 PCB, to provide a transmission line of specific impedance for a differential-mode signal. The impedance calculation formulas that I have found so far, for the common-mode and differential impedance, concern the traces with the ground plane underneath. I... 14 Feb 2005 20:58