#2n3904 transistor datasheet pdf driver#
#2n3904 transistor datasheet pdf full#

The resulting voltage should be about 40V but the 36V power net is the closest value I had in KiCad.

#2n3904 transistor datasheet pdf full#

The 30V rail is rectified using a full bridge rectifier and C7 as a smoothing capacitor. The connector carries the two outputs from the transformer, 30VAC on pin 1 and 2 and 10VAC on pin 3 and 4. Just a pretty standard power supply desing. The EEPROM memory is hard-wired to address 0 by tying all address pins to ground. For some reason it is not connected to the dedicated SDA/SCK pins The microcontroller has no EEPROM integrated, which leads to an additional EEPROM chip One capacitor just for supply stability and thatвЂ™s it. The datasheet suggests 360 and 330 Ohms for these resistors. However, the resistor values for R2 and R3 seem a bit low. The additional circuitry is pretty much the recommended design from the MOC3041 datasheet. It contains a zero-crossing detectionД¬ircuit and controls the triac U1, which in my device is a BTA16.

#2n3904 transistor datasheet pdf driver#

The MOC3041 is a triac driver and that it does. This pulls down the cathode potential and activates the optocoupler U2 which is a MOC3041. The microcontroller can control the NPN-transistor Q1 through the limiting resistor R4. The right part of the schematic is the heater control circuit. The only notable part is a big suppression capacitor (0.1uF 275V) by Tenta. The mains power is bridged over to the connector for the transformer. The left part of the schematic is about as simple as possible. We start at the top left and continue in normal reading direction. Here is the complete schematic in all itвЂ™s glory. I rebuilt the schematics of the PCB in KiCad. That all values are correct, because at some places I have the nagging feeling that the values are not matching my expectations. I took the values from resistors from their marking visible on the images. Lastly, I added all part references and as much part information as possible, i.e. I can match the position to the image of the front side of the PCB and still read parts numbers. Most of the colors are just randomly chosen, but the yellow area is the +5V VCC line and the 0V areas are marked blue.ДЄfterwards I added all the components on a second layer. Then I started with marking most of the copper traces in different colors. So this view is kind of an вЂњX-RayвЂќ view through the front side of the PCB. I started with a picture of the copper side of the PCB which I flipped horizontally, My process of reverse engineering can be seen in the following picture (click for large version). Some of the parts are similar to other вЂњflavorsвЂќ of the 858D, but some seem to be different. Now it is time to really reverse engineer the main PCB. Recently, I posted the teardown of my Saike 858D SMD rework station.