crasic

Berkeley, CA

Age: 25

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

8h
comment Laptop Motherboard Schematics
Due to pervasive Trojan activity and commercial espionage, many major devices have schematics leaked online, however finding a specific Rev of a specific PN is unlikely
2d
comment repeatedly turning an incandescent light bulb on and off every 20 seconds will cause damage to the bulb?
Incandescents have a larger tolerance to intermittent use than other bulb types (led and CFL). You can use a snubber or other soft start to extend it's life as well as the relay
2d
comment Probing with Oscilloscope Stops ADC Fluctuation
Probe Ground (the clippy side) is connected directly to earth ground, through the oscilloscope. Every time you move the probe clip you are moving your star point (topologically)
Feb
6
comment ENC28J60 connected to Arduino on SPI
Do you have access to an oscilloscope or spi sniffer? You would be well on your way to a diagnosis if you have traces of the MISO MOSI CLK and CS lines
Feb
6
comment Could I use two 120V ac Heating-Mats directly with 230V mains current?
Ive used similar heating pads and they are nichrome heaters with a fixed impedance. They are intended to be used under PID control. Since you mentioned heater controller, I'm assuming you are already doing this, using two in series is not an issue. Ideally you should have an overtemp sensor directly on the pad.
Feb
6
comment CAN bus possibilities?
CAN is a peer to peer or broadcast bus so any node can talk to any other node. As @JonRB 's comment hinted, arbitration for collisions is resolved by identifier, You can implement the protocol on whatever host controller you want. Keep in mind in certain industries, the industry Physical layer spec may override CAN so tranceivers are not as plug and play as most people would hope.
Feb
4
comment Old Text Book Current Question
Using a mathematians lens this would mean that a 2 element circuit is an example of a circuit both series and parallel as rules/laws associated with both symmetries will apply. However this somewhat of an abstraction as a real voltage source may likely physically be a multiple element net and really it's just a consequence of simplifying circuits into thevenin equivalents
Feb
2
comment SPI and ADC timing diagram
@Andyaka not necessarily, this type of ADC can be set in "continuous conversion" and the DRDY/IRQ line indicates a new result in the buffer, you can query the buffer at your leisure before the next conversion completes. Problems can occur when you do not time against DRDY and you ask for a result while it is in the middle of updating a conversion or a conversion completes while it is shifting out thiedata, I have had various intermittent bitflip issues caused by polling ADC's without interrupts.
Feb
2
revised Pull up on output pin of Buffer SN74HCT245
added 375 characters in body
Feb
2
revised Pull up on output pin of Buffer SN74HCT245
added 375 characters in body
Feb
2
reviewed Reviewed Interface RTC and Accelerometer to Arduino UNO board
Feb
2
reviewed Reviewed How many affordable lithium polymer batteries would it take to safely jump-start a car?
Feb
2
answered Pull up on output pin of Buffer SN74HCT245
Feb
2
comment 100nF MLCC bypass capacitor spontaneously exploding on 3.3V bus, how does this even happen?
TDK has additional white sheets hosted on digikey about MLCC failures under physical and thermal stress Common Cracking Modes in Surface Mount MLCC and Guide to MLCC Flex Cracking
Feb
1
comment 100nF MLCC bypass capacitor spontaneously exploding on 3.3V bus, how does this even happen?
Oh yeah thw orientation of the cap, it size, and the massive support member makes this ripe for mechanical stress failure. If this is your design you should research into mlcc flexure limits, they are surprisingly fragile components
Feb
1
comment 100nF MLCC bypass capacitor spontaneously exploding on 3.3V bus, how does this even happen?
@jms inductive spikes can exceed supply voltage significantly. You could investigate turn on noise or increase the cap rating if it's a repeated issue in the design.
Feb
1
comment 100nF MLCC bypass capacitor spontaneously exploding on 3.3V bus, how does this even happen?
Is this the only unit that failed? It could have been a cracked cap and partially failed with high ESR and failed completely on load. You will need to investigate to eliminate other failure sources like inductive spikes and significant supply noise . If the capacitor is at fault common causes are flexure (bending), bad component stock, and process defects like too much force on the picknplace or debris on pcb during placement
Jan
31
comment Why do I have to use an additional resistor with a photoresistor?
@Moussamoa the input voltage is effectively fixed, batteries and power supplies will provide whatever current is necessary at a fixed voltage. Alternatively you can use a fixed current source which will vary the voltage to keep the current constant. For dc circuit analysis you often assume that the supply voltage is a constant value regardless of load. In reality batteries and supplies have a current limit beyond which they no longer provide a constant voltage
Jan
30
comment How to set up two internet conenctions, on LAN with NAS
In terms of combining, both networks provide access to the internet, so in terms of routes they both provide the same WAN routes. If you want them on one network then you need to configure them as seperate gateways in your routing tables. You can keep them as seperate wireless networks by splitting them up in subnets - configuring routes to route between the two local networks but using the LTE or ADSL gateway depending on which wifi you connect to
Jan
30
comment How does a vacuum tube amplifier work?
@AshishAhuja I don't believe tcrosley ever claimed to be the creator of these pictures. Standards for citation are lower on a public Q&A forum than a school report or academic paper where there is a requirement/assumption of original authorship for all uncited claims. It is also certainly not a violation of copyright
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