Search found 56 matches

by redrocker
Wed Mar 17, 2010 8:03 am
Forum: General Discussion
Topic: Voltage converter
Replies: 6
Views: 1339

Re: Voltage converter

The describing equation for the OP's circuit is simply: Vout = 5 - Vin. The Kirchoff's current equation for the inverting node of an inverting amplifier is: I1 = (Vin / Rg) = -I2 = -(Vout / Rf) This assumes a 'virtual ground', or zero volts, at the inverting input, because the non-inverting input is...
by redrocker
Sun May 25, 2008 1:43 pm
Forum: Projects & Kits
Topic: A Simple Superhet by John E. Post, March 2008
Replies: 3
Views: 3721

Thanks, sghioto. I entirely missed that part of the article. Would 30 AWG wire wrap wire be a suitable substitute for magnet wire?
by redrocker
Sat May 24, 2008 7:59 am
Forum: Projects & Kits
Topic: A Simple Superhet by John E. Post, March 2008
Replies: 3
Views: 3721

A Simple Superhet by John E. Post, March 2008

I do not understand how to connect the antenna (L1) to the SA602's input amplifier. The problem is that the antenna is depicted as a transformer (see schematic below) when in reality it is an inductor. In other words, the antenna is a two-terminal device, not a four-terminal device. http://users.ade...
by redrocker
Tue Sep 25, 2007 6:01 am
Forum: Computer Programming
Topic: Need help on using AVR CodeVision C compiler
Replies: 14
Views: 11526

There is a space between the 'i' and the '++' in the for-loop declaration. Maybe that is giving the compiler fits.
by redrocker
Wed Sep 05, 2007 4:50 pm
Forum: General Discussion
Topic: Technical Dictionary
Replies: 9
Views: 3780

Here is another electronics dictionary
http://www.electronicdefinitions.com/
by redrocker
Fri Nov 24, 2006 4:55 am
Forum: General Discussion
Topic: Any spare gold soldering tip, please ?
Replies: 17
Views: 5919

Antex makes a gold-plated tip. Is this what you are looking for?

http://www.mmnewman.com/shopping/shopex ... 1&catid=20
by redrocker
Wed Nov 08, 2006 4:55 am
Forum: General Discussion
Topic: Optoisolator selection
Replies: 6
Views: 2240

Now that I have received the recommended optos, I have a question about their use. Here is the internal schematic of the part: http://users.adelphia.net/~andrewconklin/FOD050L.png The data sheet says the following: A separate connection for the bias of the photodiode improves the speed by several or...
by redrocker
Tue Oct 31, 2006 6:59 pm
Forum: General Discussion
Topic: MicroChip PIC30F Assembler
Replies: 10
Views: 3807

Point taken. I became too focused on Microchip's tools due to the reference to ASM30 in the original post.
by redrocker
Tue Oct 31, 2006 5:55 am
Forum: General Discussion
Topic: MicroChip PIC30F Assembler
Replies: 10
Views: 3807

Here is an excerpt from a 30F document: Unlike the MPASM™ assembler (for use with PICmicro® MCU’s), MPLAB ASM30 does not generate error files, hex files, or symbol and debug files. MPLAB ASM30 is capable of creating a listing file and a relocatable object file (that may or may not contain debug...
by redrocker
Tue Oct 31, 2006 5:25 am
Forum: General Discussion
Topic: MicroChip PIC30F Assembler
Replies: 10
Views: 3807

There are two gross over-simplifications in markp's desires. The first is the notion that it is possible to create an executable without a linker. The second is the underestimation of how much more complex the programming specification is for the newer, 16-bit PICs, such as the 30F series. The 16-bi...
by redrocker
Thu Oct 26, 2006 6:51 pm
Forum: General Discussion
Topic: Optoisolator selection
Replies: 6
Views: 2240

Oh, the hardware portion of my programmer is a piece of crap - I would give its schematic away for a nickel. The part that took time was the PC software. It's not great, either. I bit-bang the parallel port as fast as possible using a high speed clock available on the PC. I hope these new optos impr...
by redrocker
Thu Oct 26, 2006 12:14 pm
Forum: General Discussion
Topic: Optoisolator selection
Replies: 6
Views: 2240

Thanks Philba, I put some on order. I learned a hard lesson with this - Mouser carries much more product than they put into their catalog. I could have saved a few dollars on the 33F's by ordering from them rather than MicrochipDirect because the Mouser catalog did not list the 33F series when in fa...
by redrocker
Thu Oct 26, 2006 7:39 am
Forum: General Discussion
Topic: Optoisolator selection
Replies: 6
Views: 2240

Optoisolator selection

I am a hobbyist embarking on the conversion from the dsPIC30F to the dsPIC33F series, and since the 33F is 3.3V device, I plan to build a new programmer for it. My current home-brewed programmer uses 4N25 optos to isolate the PC's parallel port signals from the target. It is painfully slow. I had to...
by redrocker
Fri Sep 22, 2006 3:52 pm
Forum: General Discussion
Topic: Power Supply 'Hot Swapping'
Replies: 5
Views: 1711

You cannot prevent all accidents from happening. It will require some prudence on the part of the operator. Install an E-stop and LED indicator in series with the DC voltages. We had a similar circumstance in my last job wherein we hot-plugged Molex connectors to our drives and sometimes we would bl...
by redrocker
Fri Sep 22, 2006 3:20 pm
Forum: Computer Programming
Topic: Terribly new question.
Replies: 9
Views: 5040

This chip is an OTP (one time programmable). Go with a different USB chip for your project. The June edition of N&V has an article about creating an USB interface with a Microchip PIC. Investments in programming hardware for PIC's would likely be of more use in future projects.