Design

Need help understanding HP10544 osc oven circuit.
Hi - Recently, I acquired an HP ovenized oscillator (HP10544A)which was missing the proportional oven controller. I found the schematic for the oscillator at the following link: http://www.leapsecond.com/museum/10544/ After building the oven controller on a small PCB, I purposely disabled the unijunctio... 31 May 2007 06:10

"0V Vbe" current amplifier?
Is there a clever way to make a current amplifier which acts like a NPN transistor except that it has 0 Vbe? That is, with a "base" resistor of 10k and an input voltage of 100mV, 10uA gets amplified into 1mA at the "collector"? Preferably a method that does not use an IC's (opamps, etc..) ... 16 May 2007 09:37

Rocket Science
Please tell me how you would design. Application - Operate vibrating motor with 1 button battery and on/off swith. The PRIMARY desgn concern is SMALL in size - every MM is critical. Battery should operate motor for 15-30 mintues at full power - we don't want to regulate power to motor as the battery is barely enou... 29 Apr 2007 18:29

recomended lowish volume flyback vendor
Does anyone have a vendor they like working with that works NRE + production cost for low volume SMPS flyback topology transformers. I need an EP-13 size transformer designed and produced for an NCP-1012 5w dual output design. My client is low volume at around 200 per year. All the folks I currently use are be... 25 Apr 2007 23:20

10V ceramic cap at 95V DC ?
I was wondering what happens when you put too much voltage across a one of those low voltage multilayer ceramic capacitors. I took a 2.2uF 10V X7R in 1206 package, and applied 95V across it and nothing exciting happened. Leakage settled to 0.5uA after 2 minutes. Even after disconnecting for 1 minute the termina... 3 Apr 2007 17:59

Micpre of Graham
The schematic http://rapidshare.com/files/21272377/mic_amp_2.jpg looks pretty simple, but it still needs work. I found a couple of gotchas: 1. When you switch on the phantom power the Vbe of the transistors gets reversed momentarily(+17V instead of -0.7V), degrading beta and Vos. This will slowly destroy the inp... 26 Mar 2007 05:22

Which uController to learn?
PIC is king, I'm sure. But I'd like to hear from those who are using all brands. Whichever you use, what do you like about it? What don't you like about others? Suggestions re. learning? I've programmed 68000 assembly and some higher-level languages (FORTRAN; some BASIC; COBOL if forced to admit it), so no st... 25 Mar 2007 20:05

1000V high side gate drive
Gents, I'm looking for a high side IGBT gate driver for use with a 1000V bus voltage. I prefer something like an IR2110 but it is only rated for 600V. Anything else out there besides gate drive transformers? This is for a 3 phase AC induction motor inverter PWM switched at 10 - 20KHz. ... 8 Mar 2007 20:27

SPDIF amplifier
I want to amplify and distribute SPDIF to three systems over maybe 100m feeding into systems that take AES/EBU. So, thinking of putting the SPDIF through an amp and then splitting it through a 4 Way off the shelf passive F- Splitter. Can anyone recommend a cheap amp that might be suitable for this? People have sug... 6 Mar 2007 08:27

12-volt matrix input->output?
I want to turn on 4 lamps in 6 combinations. These are controlled by 3 switches in 6 corresponding combinations of contact closings. The truth table looks like this Switches Lamps A B C W X Y Z ----- ------- 0 1 0 1 0 0 0 0 1 1 1 1 0 0 1 0 0 0 0 1 0 1 0 1 1 0 1 0 1 1 0 1 0 ... 5 Mar 2007 11:15