crasic

Berkeley, CA

Age: 25

I'm a physics student at the University of California.

2h
comment efficient encryption key generation using microcontrollers
@DragonKoko it is a validated SHA256 crypto algorithm as well as a true hardware RNG. For security sake, someone could still be sniffing the connection from MCU to security chip and read the keys you load, but once this is set then the private keys are secure on the chip. Initialization should be done at a location you trust.
2h
comment How can I change the power supply from one to another?
You can use a contactor which is effectively a very robust relay (or probably rather, two independent interlocked contactors) to switch single phase power from one supply to another. Keep in mind that depending on the size of the motor, the jump in phase may cause a large instantaneous torque on the motor and can damage it, so a circuit to sense the AC phases of both power supplies and properly timing changeovers may be necessary.
20h
comment efficient encryption key generation using microcontrollers
As @IgnacioVazquez-Abrams hinted Atmel offers SPI, I2C, and SWI security chips with hardware RNG, SHA, AES, data locking and other security features. e.g. SHA204A which only needs VCC, GND, and a single Data pin in the SWI variant
20h
comment Transistor overheating in seconds when connected to usb power source
There is a schematic editor built into EE.SE, when editing your question click on the little circuit button above the text field and try to recreate your schematic as best as you can if one is not already available
20h
comment Transistor overheating in seconds when connected to usb power source
Those pictures do little to clarify unfortunately. A schematic is almost always more useful and is necessary to get answers here. I can't even read the colors on the resistor to verify what you are using. With the mess on the back of the lower picture its impossible to say what is connected to what.
20h
comment Reason why polarized electrolyic on audio line doesn't blow up
I believe from talking to people who have dealt with this that low end audio products tend to have DC biases on their output, but I haven't seen enough devices to give you my view on it
20h
comment Transistor overheating in seconds when connected to usb power source
Please provide the exact schematic you used. If it gets hot = you are pulling more current than you think, but its impossible to tell what you are missing in your understanding or what mistake you made without knowing what you did. (It is also not reasonable to expect users of this site to watch a video or extract the infor from a picture of your assembly, please provide a schematic picture or draw it in the schematic editor available on EE.SE)
21h
comment Reason why polarized electrolyic on audio line doesn't blow up
See : this question. There is likely a DC bias assumed on the input, even if you don't add it in the circuit
21h
comment Micro USB connector (data) 90 degrees up
To me it looks like there is a small pcb assembly with a vertical smt Micro-B connector soldered to it. Here is an example component. The cable sheath/insulation is flat instead of round. Cables with 90 degree connectors can be readily found like this one and this one with a flat flex cable. The term for this is a "Right Angle Micro USB-B"
1d
answered Question about Vcc
1d
comment Multiplexing two SPI Master
Do you have to use Flash? There are dual port RAM and EEPROMS available
2d
comment Germanium Power Diodes
to add one more negative. Germanium diodes will self dope and degrade from cosmic rays present across the surface of the earth . The germanium transmutes to gallium (n-type dopant) from occasional high energy gamma particles impinging on isotopic impurities in the crystal as well as Arsenic (p-type) from alpha particles caused by particle showers.
2d
comment how to derive VGA timing parameters from screen resolution?
When I did NTSC bit banging on atmega I had a large spreadsheet with all these values calculated. What you do is you trudge through the VGA specifications . Enjoy
2d
answered How do I use the on board oscillator?
2d
comment Making image data from video data stream
Many of the more advanced MCU's and MPU's have a image sensor interface and you can always use a discrete sensor controller too. Everything else is can be done in software on the MCU, but as @BruceAbbott said you need to degfine "low bandwidth" and the desired protocol
Aug
31
answered Feeding arduino with ATX standby power
Aug
30
comment power calculation for hoist motor,
Pulling out standards to calculate a simple gravitational potential energy equation seems a bit silly, but still a good answer.
Aug
28
comment Why would you use a non-contact voltage detector if you have a multimeter?
Safety. You find them more in industrial settings where technicians would have less leeway to mess with electrics without good reason. This allows you to test for e.g live wires without touching amy hookups. You can also do cool things like check which wire in am unmarked bundle corresponds to its parent end 50ft away.
Aug
27
comment Xref Net Labels in eagle
@4riy4n An "INPUT" Pin needs something to drive it, so ERC is complaining that there is a lack of "OUTPUT" pin on the same net
Aug
27
comment Xref Net Labels in eagle
When you define a component symbol you can decide the net state of each pin e.g - in, out, in/out, tristate, pwr. This determines what ERC flags comes up. You can probably ignore it if its the only issue and you don't want to deal with untangling the pin properties
1 2 3 4 5