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Hi. i am trying to configure a 555 timer to output a 20khz cycle with a 1% duty. I am having trouble because I cant get it to output a lower than 50 % duty cycle with that frequency!
Can you help me...

Hi JS, thanks for your help.
I will look it up right know and post the results.
Thanks again.
Manuel

Hello. My name is Manuel, I am 16, and I live in Argentina. I want to build an inductance meter for my coils (i am starting to design switching converters :)
I looked over some web pages on google...

Hi.
I am building a coilgun with some capacitors, and I would like to use a PIC handle the charging process. I read that gigh voltage capacitors are dangeroud, but what is it that makes electricity...

Hi.
I am building a multiplexed high power LED display, and I would like to use mosfets to control it. I would like to make a 4 x 6 display, using 6 N channel mosfets, and 4 P channel mosfets.
I...

Hi there. Thanks a lot for all your answers!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Its great to be able to ask for help and get it so quick!!!!
I will use the pull-down resistor and be sure to...

Hi. Thanks for your answer!!!!
Sorry to bother you again, my english is not very good! :) The resistor to ground will keep the transistor off even if for a tiny lenght of time the pic pin is held...

Hi. I am building a model rocket launcher with countdown, safe key, etc.
The firing fuse that lights up the motor (just a low resistance wire that heats up the engine) is conected to a logic level...

Hello. I live in Argentina (South America) and here PICs are pretty expensive. In four days, I am going on a trip to the US, to FL, and I would like to buy some PICs to use later on when I return. Do...

Hi. I am working on a project that is going to need 10 PWM output signals to charge 10 li-poly or li-ion batteries. Yeah thats a lot of PWM!!! :)
The problem is that I need a way to produce the...

Hey. Thanks for your answers. I have no idea how much current my multimeter uses to test for diodes....
Yeah, ssame here. If yuou connected the other way round, the just get hot, but they dont fry...

Hey. Thanks for all the answers. I think im going to connect a npn transistor as most of you suggested. The probem is that, as it is battery powered, i need to keep the current draw very small. Do...

Hey. Sorry to bother you again.
I have just looked in Electrical Characteristics, but i cant seem to find my answer :( I think it might be the thing called "clamp current" or sth. but im not sure....

Thanks a lot
I will look it right now!!!
Thanks again
Manuel

Hi. First of all, I want to say sorry if this is already posted, but I tried searching with no luck. I would like to know if an IO of a PIC can source a higher voltahe than Vdd. For example: PIC...

Hey. Thanks for all your help.
I dont have any experience with this tiny lithium con cells, so i hink that you must be right! :)
Anyway, this project is supposed to beep in the classes of a teacher...

Hey. Thanks for your answer. I have just checked the Energizer datasheet for the con cell CR2032. It is rated at 240 mAh, and with a pulsed drain (2 seconds, 12 times/day, 6.8 mAh), it should give...

Hi. My name is Manuel, and I am building a project around the PIC16F628A and a piezo. It is supposed to make 10 one second BEEPs everyday at a specified hour (spaced around 10 mins). I am using TMR1...

Hey. Thanks for your answers. I would like to make a battery dircharger / analizer, so the resolution will have to be quite good. The discharge rate will be about 200 - 400 mah. Can you send me any...

Hi. I want to make a current sensing device, and I read somewhere (cant remember now) that you could you a small value resistor (about 0.1R) a measure the current drop across it. But how do I...

Hi. Thanks for your help.
Yes, as you said, it would be ideal the low frequency crystal, and the timing is also much simpler :) LOL.
The LM35 outputs a linear 10 mV/`C and the LM34 is 10 mV/`F...

Hey
Thanks so much for the links. There great because the dont have interrepts :) and they are not too complicated!!!
Yes youre right 20MHz is WAY too much for this project. I could use only 32KHz...

Thanks paul. I am planning to build a temperature datalogger, that will collect data every two minutes for a month or two, so I need to get it as accurate as possible. Also, in my country, Argentina,...

Sorry in my last post, it should have been:
The variable should have been loaded with 65.000!! NOT 60.000
And when we add a thousand, do we get just 0x0000 or 465 (65000 + 1000 - 65535)??? Thanks...

hi ronsimpson!!! thanks for your help. i have two questions:
to calculate the interrupts with TMR1, I thought you had to divide the value by 66535 (0xFFFF). But, as you say, its 66536 because 0x0000...