Search found 228 matches

by saipan59
Tue Jun 10, 2008 9:43 am
Forum: SparkFun Product Questions
Topic: Buying an Oscilloscope
Replies: 11
Views: 3251

Go to your local HAM "swapfest". I went to our local one last weekend. There were 3 or 4 "old and huge" scopes for really cheap. One guy had two Tek scopes for sale. One was a Tek 475A (a very fine 250 Mhz dual trace scope, it's what I use at home), and he was asking $250 for it. He had them powered...
by saipan59
Sat May 17, 2008 5:43 pm
Forum: SparkFun Product Questions
Topic: Using a battery as a touch sensor
Replies: 11
Views: 3451

Wouldn't this have problems if your draw from the battery isn't fairly constant?
Bypass caps on the non-battery-side of the inductors will take care of it.

Pete
by saipan59
Sat May 17, 2008 9:57 am
Forum: SparkFun Product Questions
Topic: Using a battery as a touch sensor
Replies: 11
Views: 3451

You'll still need something to be at the other end of the e-field that the user is disturbing. The answer there would be to provide capacitive coupling from the touch-sensor circuit to the battery. I wouldn't think that the touch-sensing would be ground-referenced per-se. So I think my original sug...
by saipan59
Tue May 13, 2008 8:28 am
Forum: SparkFun Product Questions
Topic: Using a battery as a touch sensor
Replies: 11
Views: 3451

I just thought of an idea that has a "chance" of working: Put an inductor in series with each side of the battery, then connect a capacitor from the exposed side of the battery to the touch circuit (whatever that may be). In theory, the inductors allow the battery to supply DC power to the circuit n...
by saipan59
Tue May 13, 2008 7:07 am
Forum: SparkFun Product Questions
Topic: Using a battery as a touch sensor
Replies: 11
Views: 3451

I'm assuming that the device will be running from the battery. If so, I think making a touch-sensor out of it will be difficult, because the 'touch-signal' will be common-mode with your power supply. Or, the battery will be a relatively low impedance, and you would really like to have the touch sens...
by saipan59
Sun Apr 27, 2008 8:53 pm
Forum: PIC Microcontrollers - Software and Hardware
Topic: What Language to Program In?
Replies: 8
Views: 2225

The 'big project' is for a 24FJ64GA010. Five types of interrupts are used, with different priorities. I recently ported it to a 24H-series part. I've done smaller projects with 30F6014A, 30F4011, 30F3013, 33F, etc. Also used several 18F, 16F, and 10F parts. A lot of code for 18F2420. I have not used...
by saipan59
Sun Apr 27, 2008 6:55 pm
Forum: PIC Microcontrollers - Software and Hardware
Topic: What Language to Program In?
Replies: 8
Views: 2225

I know assembler is the most efficient size-wise, but does anyone use C? In nearly all cases, assembler is only more efficient if you are VERY good at it. For nearly everybody, you can't do better than a decent compiler for non-trivial projects. I tried both Microchip C30 and Hi-tech dsPICC, both a...
by saipan59
Thu Apr 17, 2008 10:19 pm
Forum: SparkFun Product Questions
Topic: Some help on a microcontroller project
Replies: 5
Views: 1793

I concur with Phil's recommendation of the SFE PIC board. For a programmer, a PICKIT2 (from Microchip) is a great choice. The PICs are cheaper direct from Microchip compared to most other sources. Order a PICKIT2 and 2 or 3 chips at the same time, thus meeting the minimum order and such. Another opt...
by saipan59
Tue Apr 15, 2008 12:21 pm
Forum: SparkFun Product Questions
Topic: circuit or program problems?
Replies: 8
Views: 1963

Ah, good catch!
No INTOSC on those parts...

Pete
by saipan59
Tue Apr 15, 2008 11:38 am
Forum: SparkFun Product Questions
Topic: circuit or program problems?
Replies: 8
Views: 1963

Also, depending on the CONFIG settings for this particular PIC, you may need to tie pin 38 high through a pullup.

Pete
by saipan59
Tue Apr 15, 2008 11:36 am
Forum: SparkFun Product Questions
Topic: circuit or program problems?
Replies: 8
Views: 1963

Also, you should connect pins 31 and 32 to the appropriate places.

Pete
by saipan59
Fri Apr 04, 2008 6:34 pm
Forum: PIC Microcontrollers - Software and Hardware
Topic: 3.3V PIC driving 5V LCD
Replies: 7
Views: 2959

You can drive a 5V LCD from a 3.3V PIC directly if you are doing it "write-only". If you are going to read anything from the LCD (such as the ready status), you need to check that the PIC pins are "5V tolerant".

Pete
by saipan59
Fri Apr 04, 2008 6:28 pm
Forum: SparkFun Product Questions
Topic: Any tips for this design?
Replies: 26
Views: 5564

Yes, it appears that it would work.
Be aware that it's in a very small SMT package...

Pete
by saipan59
Fri Apr 04, 2008 7:18 am
Forum: SparkFun Product Questions
Topic: Any tips for this design?
Replies: 26
Views: 5564

That's interesting. How long is that timer running? So when the PIC sends data the low pulse will trigger the 555. I wonder if 5V from the PIC would be enough to keep the 555 from triggering with a 12V VCC. Do you find that the xmtr powers up fast enough or do you lose a byte or two before it power...
by saipan59
Thu Apr 03, 2008 8:44 am
Forum: SparkFun Product Questions
Topic: Any tips for this design?
Replies: 26
Views: 5564

That may have been confusing - let me restate my suggestions: Swap the drain and source on Q2. Eliminate the connection to 5V. Add a 10K resistor from the gate of Q2 to VCC-RF. This will keep Q2 'off' when Q1 is 'off', regardless of the voltage at VCC-RF. Change Q1 to a 2N7000 (with the Source on th...