Search found 25 matches

by Stevetronics
Sun Nov 06, 2011 9:27 am
Forum: SparkFun Product Questions
Topic: Datasheet Help!
Replies: 0
Views: 300

Datasheet Help!

Hey all, I was wondering if anyone had information on an IC, the "A6651SEVT", date code 0821, marked 154M. I need to find a datasheet and I have come up dry elsewhere on teh interwebs. It seems to be a motor driver/power converter IC, found in Epson Printers, and looks to be in a 48-pin QFN package....
by Stevetronics
Sun Sep 26, 2010 12:09 pm
Forum: SparkFun Product Questions
Topic: Bidirectional Level Shifting
Replies: 3
Views: 495

Re: Bidirectional Level Shifting

Thanks guys! Zeners it is.
by Stevetronics
Sat Sep 25, 2010 11:43 am
Forum: SparkFun Product Questions
Topic: Bidirectional Level Shifting
Replies: 3
Views: 495

Bidirectional Level Shifting

Hey all, I'm working on a V-USB project, and have been looking at the issues with level shift in the usb lines. My ATmega32 HAS to run at 5v for this project, as there are other (much, much older) ics in the circuit that will _not_ run at 3.3v, despite my attempts. (I'm talking to you, Intel 8021). ...
by Stevetronics
Mon Jul 12, 2010 5:39 pm
Forum: SparkFun Product Questions
Topic: Charging two 110mAh lipos in parallel?
Replies: 11
Views: 1467

Re: Charging two 110mAh lipos in parallel?

Esklar, it all makes sense to me except the bit about changing the resistor. Why would that be necessary? With a fixed resistance, current flow should decrease directly as voltage does. Why would I want a different resistor?
by Stevetronics
Mon Jul 12, 2010 2:16 pm
Forum: SparkFun Product Questions
Topic: Charging two 110mAh lipos in parallel?
Replies: 11
Views: 1467

Re: Charging two 110mAh lipos in parallel?

Thanks esklar. That's all I needed. I never doubt the willingness of the posters on this forum to help. So rounding off to easily attainable resistors, a 22ohm resistor is fine, and after the voltage drop across the resistor is a few millivolts, I can desolder it and jumper it? Once again, thanks a ...
by Stevetronics
Sun Jul 11, 2010 8:53 pm
Forum: SparkFun Product Questions
Topic: Charging two 110mAh lipos in parallel?
Replies: 11
Views: 1467

Re: Charging two 110mAh lipos in parallel?

Ok. I am going to use and charge the batteries in parallel. So you are saying that when I first connect them, I should have a current limiting resistor between them? So for a Vdiff of ~1v (randomly chosen. is this reasonable?) and an Imax of lets say, 50mA, I should have a resistor of about 2 ohms? ...
by Stevetronics
Sun Jul 11, 2010 8:48 pm
Forum: PCB Design Questions
Topic: Displaying pin names automatically?
Replies: 1
Views: 414

Displaying pin names automatically?

In the pictures for the high altitude balloon tutorial, Nate has the pin names for the pins used displayed on top of the pads on the pcb. Anybody know how to do this?
by Stevetronics
Fri Jul 09, 2010 8:09 am
Forum: SparkFun Product Questions
Topic: Charging two 110mAh lipos in parallel?
Replies: 11
Views: 1467

Re: Charging two 110mAh lipos in parallel?

Thanks for the help. Should I attempt to only use one battery or should I somehow switch them apart for charging? 1555's are tiny, so I could use two of them, but that would be a last resort.
by Stevetronics
Thu Jul 08, 2010 8:57 pm
Forum: SparkFun Product Questions
Topic: Charging two 110mAh lipos in parallel?
Replies: 11
Views: 1467

Charging two 110mAh lipos in parallel?

Hey all, hoping for a little help on a project that I'm working on (oh yet another avr-oled watch). And I was wondering if I can charge two 110mAH batteries in parallel? Can I leave them connected for charging or do I need to use some sort of switch that separates them for charging then reconnects t...
by Stevetronics
Thu Jun 10, 2010 9:22 pm
Forum: SparkFun Product Questions
Topic: switching very high voltages
Replies: 7
Views: 772

Re: switching very high voltages

@esklar:
Clever! But perhaps a little off topic.
Back to the original question: I have done no research, but what about a relay?
by Stevetronics
Sun Feb 21, 2010 8:34 pm
Forum: Code
Topic: ATmega128 programming a CPLD over JTAG
Replies: 2
Views: 1150

ATmega128 programming a CPLD over JTAG

Hey all, I've got a project in the works that needs to program a CPLD (in this case an ATF1508ASVL in the 84PLCC package from atmel) and I was wondering if the JTAG interface on the ATmega128 would be useable for this, or if it is solely a programming interface. Any help would be great. Thanks!
by Stevetronics
Fri Feb 19, 2010 6:13 am
Forum: SparkFun Product Questions
Topic: Pulling a pin low during power-on-reset.
Replies: 12
Views: 1997

OrlandoArias, thank you. That was really, really well explained. The diode makes sense to me now. So while the circuit would function without the diode, having it improves its operation overall. Am I right?
by Stevetronics
Tue Feb 16, 2010 3:35 pm
Forum: SparkFun Product Questions
Topic: Pulling a pin low during power-on-reset.
Replies: 12
Views: 1997

The diode keeps the circuit performing like it should even in bad power situations. Makes sense. @FallingTrea: I want it to enter programming mode every time I power it up, and this will tell it to look for a programmer. Also, #PDI can't be a GPIO, it's just a system control pin. I need a pulse on t...
by Stevetronics
Mon Feb 15, 2010 7:41 pm
Forum: SparkFun Product Questions
Topic: Pulling a pin low during power-on-reset.
Replies: 12
Views: 1997

Oh! I get it! The resistor holds the line low for some time but the diode lets it return high quickly. So that way you get a roughly square pulse? (Not really square, but the rise time would be lower than just through the resistor again, right?)
by Stevetronics
Sun Feb 14, 2010 9:55 pm
Forum: SparkFun Product Questions
Topic: Howto switch AC from DC Logic?
Replies: 4
Views: 730

Look into triacs. See the sparkfun tutorial: http://www.sparkfun.com/commerce/tutori ... als_id=130
You'll have to make sure that your triac can handle the power, but even a small TO-95 package like the SFE guys use in the original proto looks to handle it fine.