Recent Posts

1

General Discussion / unkown electronic component

« Last post by johniee on February 01, 2018, 23:16:09 PM »

Does anyone know what is the function of electronic componenet A619N ?

2

Your projects / Re: overheating Circuit

« Last post by kam on December 03, 2017, 14:52:23 PM »

YES!!! In one word. 2W in such a small surface can be very very hot

3

Your projects / Re: overheating Circuit

« Last post by JardCrocker on November 13, 2017, 16:04:25 PM »

Hi,...i am a new user here. As per my observation you are dropping 4V between input and output, and at 0.5A that makes 2W, and that is a LOT of heat without a heatsink.At 2W without any heatsink, the die of the device will be at a whopping 155?C if your ambient temperature is 25?C, and the case will be 10?C less, but 145?C is still a nice way to burn your fingers.

4

General Discussion / 3 phase motor megger testing

« Last post by Greg on November 02, 2017, 04:36:42 AM »

I have a 3 phase motor   When testing with a megger do you only test from each winding to ground.
When I do a ohm meter test of the 6 wires I get a reading wirer  green 1&2.  9.7ohm       White  3&4.  9.7 ohm          Yellow  5&6   9.7 ohm readings .
This is the order in witch they wer connected to the terminal block.
When I connect any black wirer or white wirer in any order I get a ohm reading between 17 and 10 ohm  black to black or white to white black to white.
I do not under stand this layout.
Are all the wind endings going inside.
The windings do not go to earth.
Grer

5

Your projects / Current not stable in Voltage Divider

« Last post by ma1990 on October 27, 2017, 17:15:16 PM »

Hello! I recently built a voltage divider, and tested out resistors before soldering, which were in good condition. However, when I connect my divider to the HV supply my current seems to be unstable.

The current should read 210microA, but it keeps fluctuating between 218-219 even after 10 minutes of voltage running through it. I have re-tested the resistors still connected to the board with the use of a multimeter and they all still give me their correct value. I even added extra solder support to the resistors thinking that one might be lose but I have had no luck in stabilizing it.
Any suggestions?

I would greatly appreciate it,
ma1990

6

General Discussion / Re: 555 Breathing (Pulsing) LED

« Last post by urameshix on October 12, 2017, 15:30:11 PM »

Good Morning all,

I have exactly the same problem. It lights up once, and then stays off all the time.
I checked the voltage in the capacitor, and it's changing due to 555, but led does not light up.

I also tried to connect directly the led with a resistor to pin 3, and it blinks well.

Video here: https://youtu.be/XInVuIA9g8c








Any idea?

Regards

7

General Discussion / Temperature Controlled Fan

« Last post by sabareeshchambayil on August 25, 2017, 23:57:12 PM »

 I made this circuit and it worked.

http://pcbheaven.com/circuitpages/Two_Speed_Temperature_Fan_Controller/index.php

But there no control in pwm.

Turning R2 pot to both extreme end make fan run at full speed and R5  pot has no effect on the fan speed . what I am doing wrong

the NTC value is 4.7 K and Used Bc337-40 in place of BC337 and KSP2222A in place of 2N222A.


Anybody have pcb Layout of this project?

8

General Discussion / Need help with a servo motor

« Last post by Dizzdogg on July 24, 2017, 03:40:36 AM »

I have a servo motor that I can't figure out how to use (I have enclosed a picture). I've had this motor for 20 plus years and I can't find any info on it, online or anywhere else (I'm new to servo motors by the way). Any and all help will be greatly appreciated.

9

General Discussion / Temperature based high frequency PWM fan controller?

« Last post by ksuuk on June 23, 2017, 11:08:27 AM »

Hi,

About  the High Frequency PWM Fan Controller ( http://www.pcbheaven.com/circuitpages/High_Frequency_PWM_Fan_Controller/ )

How to modify this 4 pin circuit, so that it works automatically based temperature?

10

Your projects / Re: Step motor driver

« Last post by kam on June 17, 2017, 10:33:32 AM »

Sorry but cannot understand. I think that you mean that if you try to rotate fast the stepper stops. This is normal. Steppers have a maximum RPM that you may exceed.