Search found 28 matches
- Tue Nov 06, 2007 10:42 am
- Forum: General Discussion
- Topic: Hey Al, try Allied...
- Replies: 11
- Views: 5820
Yeah, these catalogs are ridiculous. Is there a way to get them to just NOT send them any more? They really should have a checkbox on their online ordering form: [X] Please send me ENORMOUS PHONE BOOK SIZED CATALOG four times a year. that you can uncheck before issuing your order. Or maybe one like:...
- Mon Nov 05, 2007 6:57 pm
- Forum: General Discussion
- Topic: Price too high for four channel AD chip???
- Replies: 15
- Views: 6437
2 layer boards in Qty 50 should be very cheap per piece. Lots of PCB fabs have online quote calculators so you can do some what-ifs without getting formal quotes. I've never sent anything out to be fabbed, but I look foward to doing so once I'm more confident in my designs. This may be a useful res...
- Fri Nov 02, 2007 2:57 pm
- Forum: General Discussion
- Topic: Problems with Futurlec
- Replies: 21
- Views: 10687
This is the worst company i have ever dealt with. My first order from them took a long time to come. Longer than I'd have expected, but it did arrive, and it did arrive in toto. My second order from them was a much larger order, and I paid for 3 day shipping and it arrived three days from when they...
- Fri Oct 26, 2007 11:41 am
- Forum: General Discussion
- Topic: Electronics Beginner
- Replies: 14
- Views: 7350
i mean i collect junk as it is i have several old 3.5 floppy disk drives i can scrap for parts and some old cdroms as well Scrap parts are a great way of pursuing an electronics on the cheap. I pull parts out of a bunch of old salvaged crap all of the time, though doing it requires some soldering /...
- Fri Oct 19, 2007 11:07 am
- Forum: General Discussion
- Topic: Comp USA out of business?
- Replies: 16
- Views: 8277
- Fri Oct 19, 2007 9:18 am
- Forum: General Discussion
- Topic: Half-watt resistors in parallel?
- Replies: 23
- Views: 10630
- Wed Oct 03, 2007 10:56 am
- Forum: General Discussion
- Topic: Half-watt resistors in parallel?
- Replies: 23
- Views: 10630
It's interesting to me that resistors in series are preferred over in parallel. Is this primarily to prevent arcing over the (smaller wattage) resistors? While the voltage IS very high (20kV is likely, on the top end) woiuldn't putting smaller wattage resistors in parallel dissipate current better a...
- Tue Oct 02, 2007 2:17 pm
- Forum: General Discussion
- Topic: Half-watt resistors in parallel?
- Replies: 23
- Views: 10630
Half-watt resistors in parallel?
I want to discharge a CRT through a 1M Ohm resistor so as not to damage the cascade rectifier that's possibly holding some of the charge. I only have 1/2 watt resistors at 1M Ohm, however, and it's advised to use 3W or higher rated resistors. It would make sense to me intuitively to be able to use s...
- Wed Sep 19, 2007 12:04 pm
- Forum: General Discussion
- Topic: Charging While Wall-Warting
- Replies: 45
- Views: 19019
The tab on 7805s is the same as the common reference pin, so one on one side of heatsink, and other on other side, shouldn't be a problem. From the schematic, only one 7805 works at a time. I suspect (without doing the math) that if the 3.3V regulator input is moved from 5V to 12V/8.2 (via addition...
- Tue Sep 18, 2007 10:11 am
- Forum: General Discussion
- Topic: Charging While Wall-Warting
- Replies: 45
- Views: 19019
the cell pack voltage, which is 9.8, which means you would use 9.8 in your charge calculation, not 8.4 volts. 12v - 1.0v for diode - 9.8 for target cell pack charge voltage = 1.2v / 0.050 = 24 ohm resistor, then. I've got a 47 ohm in there from overnight that's charging today. It looks like the cel...
- Mon Sep 17, 2007 10:06 am
- Forum: General Discussion
- Topic: Charging While Wall-Warting
- Replies: 45
- Views: 19019
I get 16mA charging through 220 Ohms (you forgot to subtract the voltage across the batteries from 12V) :) Cheers, D'oh! I'm getting 48 ohms now. 12v - 1.0fv - 8.4v = 2.5v. 2.5v / 0.050mA = 48 ohms. Your new pack voltage (nominal) is 8.4 volts, but the charge voltage should be calculated first: v=8...
- Sun Sep 16, 2007 8:08 pm
- Forum: General Discussion
- Topic: Charging While Wall-Warting
- Replies: 45
- Views: 19019
It's too bad you cant use NiMH cells here, as they have a bit more capacity. I'm going to find a place on line that has inexpensive NiMH AA cells (I need to stick with AA because of their size.. I need that thickness for my case) that are rated at 2500mAh-ish. I see AA's for sale on eBay and on som...
- Sun Sep 16, 2007 7:48 pm
- Forum: General Discussion
- Topic: Charging While Wall-Warting
- Replies: 45
- Views: 19019
- Sun Sep 16, 2007 7:30 pm
- Forum: General Discussion
- Topic: Charging While Wall-Warting
- Replies: 45
- Views: 19019
- Sat Sep 15, 2007 10:48 pm
- Forum: General Discussion
- Topic: Charging While Wall-Warting
- Replies: 45
- Views: 19019