Search found 1554 matches

by dyarker
Sun Oct 26, 2003 8:43 pm
Forum: General Discussion
Topic: Is it possible to parallel transformers
Replies: 17
Views: 2871

Re: Is it possible to parallel transformers

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>How much wattage am I getting out of the system at 1A?<hr></blockquote> P = (I^2) * R P = (1 Amp ^2) * 4 Ohms = 4 Watts<p>If you double the current through a fixed load (like 4 Ohms) it means double the voltage too, so...
by dyarker
Sun Oct 26, 2003 1:10 am
Forum: General Discussion
Topic: Cascading linear regulators
Replies: 8
Views: 1676

Re: Cascading linear regulators

Cascading is the way to go. Use LDO regulators. Start with like Fairchild KA278R33TU, a TO-220 3.3V with 0.5V dropout. Then ILC7082AIM525X for 2.5V. ILC7801AIM5ADJX adjustable for 1.2V. Check the Mouser catalog if you need different current ratings and Very Low Drop-Out regulators.<p>Each following ...
by dyarker
Sat Oct 25, 2003 11:53 pm
Forum: General Discussion
Topic: Is it possible to parallel transformers
Replies: 17
Views: 2871

Re: Is it possible to parallel transformers

Ah, more info...<p>The current equals the square root of the power divided by the resistance.<p>I = (68Watts / 4Ohms)^0.5 = 4.123Amps<p>The voltage eguals the square root of the power times the resistance.<p>E = (68Watts * 4Ohms)^0.5 = 16.492Volts<p>If the 68W speaker rating is PEAK WATTS a 5 to 6 A...
by dyarker
Sat Oct 25, 2003 7:02 am
Forum: General Discussion
Topic: stable clock timer..for a different LED clock
Replies: 18
Views: 3690

Re: stable clock timer..for a different LED clock

The zener circuit is absolutely tolerant of input variation. Zero to 5.1V to zero every time.
by dyarker
Sat Oct 25, 2003 6:51 am
Forum: General Discussion
Topic: telephone interface
Replies: 6
Views: 1395

Re: telephone interface

Correction: Will work if the jacks are wired in parallel. For example, if you have two phone numbers in the house, one or more jacks will be wired for one number, and other jack(s) wired for the other number.<p>Cheers
by dyarker
Sat Oct 25, 2003 6:42 am
Forum: General Discussion
Topic: Is it possible to parallel transformers
Replies: 17
Views: 2871

Re: Is it possible to parallel transformers

The thing to watch when paralleling transformers is getting the phase right. Two identicle transformers probably have the same relative phases on the leads.<p>To check, connect the primaries in parallel, then one lead of the secondaries. Apply signal to the primary. The two open secondary leads shou...
by dyarker
Thu Oct 23, 2003 10:58 pm
Forum: General Discussion
Topic: stable clock timer..for a different LED clock
Replies: 18
Views: 3690

Re: stable clock timer..for a different LED clock

Instead of resistor divider, use resistor to a 5.1V or 4.7V zener to ground after the diode connected to a transformer lead (low voltage side of course). That gives squarer pulses. A low value capacitor in parallel with the zener filters power line noise and thermal noise generated by the zener.<p>I...
by dyarker
Tue Oct 21, 2003 8:24 pm
Forum: General Discussion
Topic: stable clock timer..for a different LED clock
Replies: 18
Views: 3690

Re: stable clock timer..for a different LED clock

For real reliability use the 60Hz power line for the frequency source, and divide a crystal oscillator to 60Hz. Then when the power goes off, batteries provide backup power, and a missing pulse detector switches in the crystal pulses until 60Hz power returns. Putting battery power to the LEDs throug...
by dyarker
Sat Oct 18, 2003 7:51 pm
Forum: General Discussion
Topic: Problem with motorhome lighting
Replies: 7
Views: 1263

Re: Problem with motorhome lighting

I agree with sundancer87, there is a problem. Those transistors are large enough to drive head lights.
by dyarker
Fri Oct 17, 2003 9:14 pm
Forum: General Discussion
Topic: Problem with motorhome lighting
Replies: 7
Views: 1263

Re: Problem with motorhome lighting

Even big transistors need resistors in series with the base.<p>Or, If the wires from the transistors to the lamps have worn insulation, going over bumps could have caused a short. That could have caused an emitter/collector short. The lamps stay on when the vehicle is still or on smooth road.<p>Or, ...
by dyarker
Sat Oct 11, 2003 10:55 pm
Forum: Robotics
Topic: Stamp reading RC Receiver signal to servo
Replies: 2
Views: 1981

Re: Stamp reading RC Receiver signal to servo

I've never worked with servos (yet), but I recognize the symptoms.<p>A micro-controller input has a very high impedance (probably CMOS). Add a resistor from signal line to ground, to increase the load on the RC receiver to something closer to what it expects to drive. I'd start at 10K Ohms.<p>It may...
by dyarker
Sat Oct 11, 2003 10:16 pm
Forum: General Discussion
Topic: Help Micro Circuit - 1 button switch to 3 led cycle cant
Replies: 6
Views: 1686

Re: Help Micro Circuit - 1 button switch to 3 led cycle cant

**Moved from Robotics Forum** I think it nearly impossible within 10mm x 50mm because blue LEDs need 3.9V to 4.5V. Including the current limiting resistor you'll need 5.5 to 6 volts. ______________________________ Proposed - Two AA cells in series. A circuit board the same width as AA diameter. On o...
by dyarker
Sat Oct 11, 2003 10:11 pm
Forum: General Discussion
Topic: Signal sensing circuit
Replies: 5
Views: 1467

Re: Signal sensing circuit

250 ft. is a L O N G way to go for a microphone. Does the mic work, without hum, when connected close to paging amp? Is the PA input labeled "MIC"? You can't just parrallel the mic with the phone system line either.<p>What kind of plug on the mic? Three conductor with push-to-talk switch sharing one...
by dyarker
Fri Oct 10, 2003 1:11 am
Forum: Robotics
Topic: Help Micro Circuit - 1 button switch to 3 led cycle cant
Replies: 2
Views: 2160

Re: Help Micro Circuit - 1 button switch to 3 led cycle cant

**Moved to same topic in General Forum**<p>[ October 11, 2003: Message edited by: Dale Y ]</p>
by dyarker
Thu Oct 09, 2003 11:35 pm
Forum: General Discussion
Topic: Signal sensing circuit
Replies: 5
Views: 1467

Re: Signal sensing circuit

Did you spell "Convayent" correctly? A search on Google resulted in ZERO hits. It's possible the company doesn't have a web site, but very unlikely that NOBODY is talking ABOUT them. So much for just looking it up and giving you an exact answer.<p>And, since you're asking here, I assume the manual i...