crasic

Berkeley, CA

Age: 25

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

2d
comment CAM 5 LASER CUTTER : needing to change the laser tube
It's laser and your should read the manual lest someone dies
Jul
25
reviewed Reviewed i want to create a set of sensors to be mounted on my fingers and distance between the two is measured by them. What kind off sensor I can use?
Jul
25
revised Raspberry Pi Intercom, switch using transistor or relay?
added 2299 characters in body
Jul
24
comment Raspberry Pi Intercom, switch using transistor or relay?
Relays require a moderate amount of current to maintain in the switched on state, the transistor "buffers" the RPI signal so that you are not pulling a lot of current from the microcontroller GPIO. Rb sets the base current to keep the transistor in saturation (Switched on). Diode D1 is a protection diode, inductive elements will generate a reverse voltage spike when the current in them start to decrease (transistor shutting off), the diode shunts this spike to ground to avoid damaging the transistor.
Jul
24
revised Raspberry Pi Intercom, switch using transistor or relay?
added 13 characters in body
Jul
24
answered Raspberry Pi Intercom, switch using transistor or relay?
Jul
24
comment Is a LCD backlight adjustable?
It entirely depends on which LCD assembly you have in mind.
Jul
22
comment Controlling valves the efficient way
Solenoids get driven by a relay. Relay is connected to a 24 V supply. A transistor switch or other buffer is used to control relay from an electronic source of some kind. Bufferinput can be from whatever you like e.g. push button, 555, or microcontroller. This buffer stage is what lets you mix low voltage sources with 24V relay. The easiest way today is probably an arduino. There are relay drive shields available
Jul
21
revised Error in Magnetometer Readings
cleaned up text math
Jul
21
comment Error in Magnetometer Readings
@GeorgeHerold The error term is detector accuracy/noise, and is typically constant in magnitude, there is an average error of 10nT even at 0 field readings. A detector may have error term that depends on the magnitude, but this requires a different error propagation term. His calculation is to determine the total magnitude of detector error, which may be very small relative to the magnitude of the measured field vector.
Jul
21
comment Error in Magnetometer Readings
Keep in mind for orientation, the earth surface field is fairly heterogeneous and there is a lot of magnetic noise in our environment. A 10nT error is approximately 5000x less than the average surface field magnitude (0.5 G or 50uT). Your environmental noise will be signficantly higher than this, otherwise your error propogation is correct in magnitude (see this list of handy formulas )
Jul
17
comment VGA to S-video/video converter won't work
Is it a cable or an actual converter box? S-video signaling (Chrom/Lum) is incompatible with VGA (RGB), however many videocards are capable of outputting SVideo as video out and some may multiplex a s-video output into the vga signal lines and provide a cable with the product, there is no standard for this and it is manufacturer specific .
Jul
17
awarded Nice Answer
Jul
17
reviewed No Action Needed Battery Ampere-hour rating vs Battery Amps (not an experienced user)
Jul
17
reviewed No Action Needed Can I tell the voltage of High Power Transmission lines by its Type?
Jul
17
reviewed No Action Needed MOS gain, how much is it, Bipolar as a key
Jul
17
reviewed No Action Needed Why is the Ampere the only SI fundamental unit for electricity?
Jul
17
revised single layer vs double layer PCB?
edited body
Jul
17
answered single layer vs double layer PCB?
Jul
17
awarded Enthusiast
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