Search found 1555 matches

by dyarker
Tue Nov 11, 2003 4:27 am
Forum: Robotics
Topic: Logic operators as numbers
Replies: 5
Views: 2232

Re: Logic operators as numbers

Do you have a bar bet with a freshman math major?<p>Kind of interesting. Wierd, but interesting.<p>I don't see any use for it either. In a strange twisted way it looks like FPGA programming. "A" and "B" as input pins. "Z L G E" as flash register bits inside setting what operation to do.<p>Binary opt...
by dyarker
Tue Nov 11, 2003 12:50 am
Forum: Robotics
Topic: Least integer again.
Replies: 6
Views: 2716

Re: Least integer again.

Geez, all that and I forgot the "proof".<p>Given: 1. For any number of bits greater than zero, there is an even number of possible states. 2. In twos compliment binary arithmatic the MSB is defined as "zero" for positive and "one" for negative. 3. In twos compliment binary arithmatic all bits set to...
by dyarker
Mon Nov 10, 2003 11:16 pm
Forum: Robotics
Topic: Least integer again.
Replies: 6
Views: 2716

Re: Least integer again.

Take the two bit number as the simplist case. A sign bit and a value bit. There are four states:<p>1 1 = -1 1 0 = -0 0 0 = +0 0 1 = +1<p>for an equal number of positives and negatives. On the other hand, in twos complement:<p>1 0 = -2 1 1 = -1 0 0 = 0 0 1 = +1<p>for there being one more negative in ...
by dyarker
Mon Nov 10, 2003 8:55 pm
Forum: General Discussion
Topic: Please Help - My Power supply broke
Replies: 13
Views: 2082

Re: Please Help - My Power supply broke

Sounds like inductive kick blow something inside the power supply. If you're lucky, just an internal fuse. Less lucky, the output transistor/regulator IC.<p>Take bodgy's advice, check the board carefully. Melted solder may have run and shorted traces. Also look for black burn marks between traces an...
by dyarker
Sun Nov 09, 2003 7:53 pm
Forum: General Discussion
Topic: Lead acid battery
Replies: 11
Views: 3422

Re: Lead acid battery

Sealed batteries don't leak, even if up-side-down. Do not use automotive batteries, for this and other issues mentioned.<p>For longevity and safety use the same type APC used. A different brand of the same type may be less expensive.
by dyarker
Sat Nov 08, 2003 8:07 pm
Forum: General Discussion
Topic: Antenna design for LIPD 433Mhz
Replies: 5
Views: 1201

Re: Antenna design for LIPD 433Mhz

You can't (legally) change the antenna on a no-licence transmitter. The transmitted power in any direction is what must designed to. Not the power out of the transmitter to the antenna.<p>That's why manufacturers must use soldered in, reverse connectors, or custom connectors on the antennas. To keep...
by dyarker
Fri Nov 07, 2003 4:02 pm
Forum: General Discussion
Topic: Television Problem
Replies: 5
Views: 1098

Re: Television Problem

Do you still have the problem when the cell phone is moved farther from the TV?<p>How long are the pauses? (In case you don't have a cell phone.)
by dyarker
Thu Nov 06, 2003 8:26 pm
Forum: Computer Programming
Topic: Need windows app. for follow up to centipede article
Replies: 7
Views: 3534

Re: Need windows app. for follow up to centipede article

Have you picked a sensor yet? 'cause that will strongly influence the format. Smaller is better for serial comm. Bit rate equals X pixels times Y pixels times frame rate tines (bits of depth plus 2 for start and stop bits).<p>So with 320 x 240, 10 frames/sec, and comm port set to 6N1, the serial bit...
by dyarker
Wed Nov 05, 2003 3:47 am
Forum: Robotics
Topic: Remote control reciever
Replies: 4
Views: 2656

Re: Remote control reciever

Do you mean each joystick has four wires? Two for up/down, and two for left/right? Eight wires total?<p>Or, four wires total for two joysticks?<p>For each direction use two optocouplers with the LEDs in parallel but reverse polarity. Take up/down for example. In center neither LED is lit, so both op...
by dyarker
Sun Nov 02, 2003 8:39 pm
Forum: General Discussion
Topic: Is it possible to parallel transformers
Replies: 17
Views: 2877

Re: Is it possible to parallel transformers

If you're getting enough volume, then a second transformer is effective for the job . The distortion should be cured, and you should get a little more volume before distortion reoccurs.<p>On the other hand, if the object is getting the max out, 2 Amps does not equal 5 Amps.<p>-----------------------...
by dyarker
Sat Nov 01, 2003 2:23 am
Forum: General Discussion
Topic: Can somebody help me design a power supply?
Replies: 13
Views: 2316

Re: Can somebody help me design a power supply?

No chip by itself it going to invert +12V to -12V regulated at 10 Amps. It will need a power transistor and other parts. Check App Notes at sites like Maxim for suggested schematics.<p>There is a way to avoid the negative supply by using two LM3886s per channel. I'll do a schematic and put it on my ...
by dyarker
Sat Nov 01, 2003 12:33 am
Forum: General Discussion
Topic: Is it possible to parallel transformers
Replies: 17
Views: 2877

Re: Is it possible to parallel transformers

Surplus resellers are much cheaper. But, you say you're getting enough volume and want to clean-up distortion. So you don't need enough power to drive the LM3886 and speaker to full rated power. Parallel a second transformer (like you originally asked), use a rectifier rated 2 or more Amps, and two ...
by dyarker
Wed Oct 29, 2003 7:35 pm
Forum: General Discussion
Topic: Is it possible to parallel transformers
Replies: 17
Views: 2877

Re: Is it possible to parallel transformers

Thanx for the link, I down loaded the spec sheet.<p>Have you looked at page 16, right column? It discusses a 40 Watt, 4 Ohm, amplifier.<p>Note 12 on page 4 says the tab is internally connected to the negative supply pin. That means the heatsink cannot be connected to ground, or the LM3886 must be at...
by dyarker
Tue Oct 28, 2003 10:26 am
Forum: General Discussion
Topic: Can somebody help me design a power supply?
Replies: 13
Views: 2316

Re: Can somebody help me design a power supply?

300Watts / 13.8Volts = 21.74Amps <p>Yeah, kinda high for the cigarette lighter, probably about max for the alternator. Alternators are commonly 45-50Amps. Larger cars with air conditioning and "towing package" may have 75+Amp alterators. Ditto pick-up trucks, campers. Allowing for head lights, heate...
by dyarker
Tue Oct 28, 2003 9:15 am
Forum: General Discussion
Topic: Audio into phone line
Replies: 9
Views: 1477

Re: Audio into phone line

You should read Tommy Volts' Telephone Interface thread in this forum. I just got a little long winded over there. But, what applies to listening to a phone line also applies to putting in a signal.<p>To combine stereo to mono you'll need two resistors, so one channel doesn't drive the other.