Activity for Olin Lathrop‭

Type	On...	Excerpt	Status	Date
Answer	—	A: High power LC circuit with programmable resonant frequency What you are asking for is totally unrealistic, and your numbers don't add up. With 10 mH and 80 µF, the resonant frequency is 178 Hz. Getting down to 1 Hz even with 10 mH would require over 2.5 F. Keep in mind that with the inductance fixed, the capacitance required for resonance is inver... (more)	—	11 months ago
Answer	—	A: Titanic submarine control considerations I don't have any special knowledge about how submarines get controlled, so this is mostly speculation. I expect that the actual controls are fine. There seem to be the necessary degrees of freedom, and as you say, people are already familiar with the interface. In that sense I don't see anything... (more)	—	11 months ago
Answer	—	A: Sensing 3 states in a single mcu pin using firmware Starting with your first circuit: It seems a little klunky, but should work. I don't like the D1 and D2 diodes. The reason I placed D1 is to avoid triggering the mosfet with very low voltage like 2V to 4V. Is D2 really necessary? The input voltage threshold for sensing high is the 8.2 V... (more)	—	11 months ago
Answer	—	A: How to change the polarity of an input using a single switch? The difference between your two options is which polarity the input floats to when left open, and whether there is an overall inversion. Adding the inversion in the firmware would require one more pin from the chip. Not necessarily. I was envisioning inversion or not would be specified by conf... (more)	—	11 months ago
Answer	—	A: Variant of a Mosfet's Gate-Source protection If the TVS truly clamps the "+12V" line to 25 V, then the VGS of Q1 can't exceed 25 V. However, if you want to limit the gate voltage, limit the gate voltage. A Zener between gate and source guarantees that directly. You may still want the TVS to clamp the incoming power voltage for other reason... (more)	—	11 months ago
Answer	—	A: Why do I need electrodes for ECG measurements? The electrodes electrically connect to the skin in order to pick up tiny signals produced by the heart muscles. Electrically you're a bag of saltwater. Your skin (the bag) has a relatively high resistance. The innards (the salt water) has relatively low resistivity. To get good signal to nois... (more)	—	11 months ago
Answer	—	A: Synchronization of clock of satelite with devices here on the Earth First, the time dilation experienced by a satellite is tiny on a human scale. It takes sophisticated algorithms and lots of processing power to measure time differences between a spot on earth and various satellites. That's how GPS works. Early GPS receivers were rack-mounted boxes before integrat... (more)	—	11 months ago
Answer	—	A: Oscillator with non-rechargable battery There actually seem to be two different questions here. Can a primary (non-rechargable) battery be damaged by forcing reverse current thru it? Yes. Primary batteries are only intended to source power, not sink it. Forcing reverse current thru them, especially for significant lengths of time, ... (more)	—	11 months ago
Answer	—	A: Confusion in operation of analog computer The poteniometers (what you label as "variable resistors") are almost certainly just floating pots. If their ends were permanently connected to power and ground, then they'd be voltage sources, not pots. You might temporarily connect the top terminal to power, the bottom to ground, and measure the... (more)	—	11 months ago
Answer	—	A: High Speed Digital Communication Bus Probing One of the first things you should do is provide a connection for the scope probe ground. If you think you'll be regularly looking at signals on this board, then one of those little loops or pins to clip a scope probe too would be useful. If it's a one-off problem, then just a thru-hole pad would b... (more)	—	11 months ago
Answer	—	A: SDR SDRAM PCB Timing Budget It would help to provide links in your question to the datasheets. Without the datasheets I can only give general advice. Look a the memory datasheet and see what the setup and hold time requirements are. There is always a window of time around a clock edge where the data must be held steady on ... (more)	—	12 months ago
Answer	—	A: How is it possible to perform a open circuit test on a induction motor? Your basic problem is that the motor needs some applied power to generate any EMF, but if you apply that power then its not an open circuit test. For a true induction motor you're probably stuck. You'll have to measure various parameters separately while the motor is being driven. By measuring t... (more)	—	12 months ago
Answer	—	A: Over-voltage protection for device with photovoltaic cell source If you don't care about efficiency of the overall system, then a zener to limit the voltage will work. You are right in that a series resistor is not needed since the source is power-limited. One problem with a zener is finding one guaranteed to limit the voltage to the 5.5 V maximum while not ge... (more)	—	12 months ago
Answer	—	A: Calculate values of externally excited DC generator/motor Your generator constant is 2 V per Webber-Hz, or 2 V/(Wb Hz) = 2 (V s)/Wb. You somehow got a value of 5. The rest of your calculations are probably off due to that. Added I didn't have much time when I wrote the above, but can delve into this more now. From your first measurement, we can s... (more)	—	12 months ago
Answer	—	A: Role of C2 (bypass capacitor) To properly answer this question, you need to show us a real circuit with a capacitor across the supply. There are various reasons a capacitor across a power supply might make sense. Protecting the supply from thermal noise created by a resistive load is way way down the list of likely explanatio... (more)	—	about 1 year ago
Answer	—	A: DC offset correction loop (DC servo loop). What's its advantage, compared to a high-pass RC filter? In addition to what Andy said, the DC servo method doesn't add impedance to the signal. Note that in your bottom circuit, the signal with the DC offset removed has an impedance of 1 MΩ at DC. In your case it doesn't matter since the signal is only going into an opamp input. In other cases ... (more)	—	about 1 year ago
Answer	—	A: How can I fix this 4-20 mA current loop to source current that matches current sink on its input? You are making this way too complicated. Go back to the basic problem definition, which is you want to get a digital reading of the current sunk by a current sink, with the valid range being 4-20 mA. It seems you chose the A/D you did because it is advertised to be able to directly read 4-20 mA c... (more)	—	about 1 year ago
Answer	—	A: Is a current-dependent current source and a current mirror the same thing? It's not clear that the problem is. It seems you want to interface to this "digital air pressure regulator" via two 4-20 mA current loops. For reading the output, it should be as simple as a 24 V power supply with a resistor in series. A 250 Ω resistor, for example, will give you a 5 V sig... (more)	—	about 1 year ago
Answer	—	A: What is a good PCB-layout? I have also designed and ordered a PCB It seems rather pointless to ask after you've already ordered the board. only uses THT-components That's just plain silly. This is the kind of thing that you might see from a clueless hobbyist, but is totally unacceptable from an electrical engineering... (more)	—	about 1 year ago
Answer	—	A: What is the role of master clock speed on DAC In protocol I2S we have 4 signal: 1.data 2.lrck/fck (frame synchronizer) 3.bck (bit clock) 4.mck/sck (master clock) Not really. IIS really only has 3 signals: bit data, bit clock, and left/right indication. Take a look at the actual IIS protocol from NXP. Some implementations do use a "master... (more)	—	about 1 year ago
Answer	—	A: What does it mean for a signal to have impedance? Impedance Yes, impedance is "extended" resistance. Impedance is really a complex value, with resistance it's real part. The imaginary part represents pure inductance or capacitance (with opposite sign). Sometimes we say "impedance" when really only the resistance is relevant. That's OK since r... (more)	—	about 1 year ago
Answer	—	A: Testing instrumentation amplifier with differential signal I think the biggest reason is that it may be difficult to control your function generator with an output of only 5 mV. Some function generators have different output ranges that are switched, then a volume knob that lets you select from 0 to the maximum for the current range. Even if it has a 100 m... (more)	—	about 1 year ago
Answer	—	A: Using arc trace routing instead of 45 degree trace routing The best route is a straight connection between the two points being connected. Of course that's not always possible due to other objects being in the way, or to be able to route other connections. I think most auto-routing software uses 45° bends because that's a reasonable tradeoff between ... (more)	—	about 1 year ago
Answer	—	A: Should a fake user's posts be deleted if the fake user has subsequently been deleted by the site It's a balance. On one had, we want to be a store of knowledge. It doesn't matter what prompted a particular piece of information to be posted if it serves the long term purpose. We also don't want volunteers that wrote answers in good faith feel like they wasted their time because the original ... (more)	—	over 1 year ago
Answer	—	A: How Relay inrush current limiter works? It's a current limiter, not eliminator. The current is always supposed to flow, but be limited at startup to avoid high inrush current. All the relay does is short out R103 when activated. The relay starts out off, so R103 is in series with the input power when the device is first plugged in or ... (more)	—	over 1 year ago
Answer	—	A: how to figure out the max power of a transformer? If there isn't a VA rating on the label or published in a reliable source, then you have to guess. There are several clues that can be used: Look at the size of the primary wires. That gives you an upper bound on the primary current. You know this is meant for 220-240 V systems, so between thes... (more)	—	over 1 year ago
Answer	—	A: What we call this opamp configuration? [SOLVED] What we call this opamp configuration?   A mess. What's the advantage and the disadvantage of this circuit? This can't be judged without the stated objectives. It might be useful for keeping undergrads busy trying to analyze this circuit. And what's the purpose of the L2 ... (more)	—	over 1 year ago
Answer	—	A: Audio OpAmp requirements The specs you need from an opamp in an audio circuit are somewhat dependent on the particular circuit. As you state, requirements of good audio circuits are high signal to noise ratio and low distortion, relative to many other analog circuits. The noise figure of an opamp is usually a fixed value... (more)	—	over 1 year ago
Answer	—	A: Why arc welding does not require high voltage to arc? It takes high voltage to start the arc. Once started, the air is ionized, and becomes fairly conductive. It then takes much less voltage to keep the current flowing to sustain the arc. This also explains why you have to touch the terminals together to start the arc. Touching shorts the output, ... (more)	—	over 1 year ago
Answer	—	A: What Sine-Wave Oscillator can be controlled with a microcontroller? pure stable sinusoidal wave This is impossible. Forget it. Go home. No matter what you do, there will always be some noise added to the sine wave. Some random noise and some harmonic distortion are inevitable. (more)	—	over 1 year ago
Answer	—	A: Unterminated SPI bus needs expansion board to work properly At 1 MHz it's probably not transmission line effects. It's not clear from your question whether the SPI bus works on the main board with the expansion board connected, but not when it's not connected. If so, I expect you're right about the additional capacitance. An easy way to check this is to ... (more)	—	over 1 year ago
Answer	—	A: How to check realistic specs of small solar panel? Your proposed circuit will work, but "before the voltage drops significantly" is rather wishy-washy. I would at least use a second meter to measure the current. What you really want to know is the power, which is the voltage times the current. With two meters you can sortof eyeball it and find a... (more)	—	over 1 year ago
Answer	—	A: Possible stray current corrosion in reinforced concrete First clarify where this leakage current will be flowing. You seem to think that some parts of the solar panel will generate a small current thru the rebar into the ground, but where is the closed loop? The polarity also matters. Current flowing one direction from steel to dirty water causes cor... (more)	—	over 1 year ago
Answer	—	A: How to calculate the voltage of a coil? calculate the voltage that will center the magnetic field of a coil This is not possible since the voltage has no effect on the position or shape of the magnetic field. The position and shape are fixed by the position and shape of the coil. But the higher the tension, the wider the magnetic fi... (more)	—	over 1 year ago
Answer	—	A: What is the difference between rise/fall time and Turn-On/off Delay Time? In general, the on/off delay is how long it takes from changing the input until the output starts to do something. The rise/fall time is how long it takes to do the something, once it starts doing it. Your first FET driver datasheet is a good example: The switching characteristics are idea... (more)	—	over 1 year ago
Answer	—	A: Is it possible to calculate the rise/fall time of an operational amplifier ? Rise and falls times are limited by the maximum slew rate the opamp can produce. This is something you look up in the datasheet. Note that the slew rate might be dependent on supply voltage and possibly other factors. Or, the datasheet might just give a single minimum large-signal slew rate for th... (more)	—	over 1 year ago
Answer	—	A: A community-maintained list of abbreviations used in electrical engineering? I was the one who started that list Elsewhere. I thought the same as you, that a few common abbreviations would be good to have in a single place. However, it quickly turned into a mess. After only a few days I could see it was a mistake. People added whatever obscure abbreviations they could... (more)	—	over 1 year ago
Answer	—	A: Buck-boost converter fed from split input supply One possibility is to use a transformer. The power input can then come from across the plus and minus input power. The output can be referenced to whatever you like, which in this case would be ground. The output current would always return to ground, so not effect the current balance between the ... (more)	—	over 1 year ago
Answer	—	A: Low-pass filter after the output DAC in CD players I don't know what the book has in mind, but your first point is the main reason I would want to filter out the high frequencies with passive analog components. Low noise and low distortion are important in audio. It makes a real difference when the amplifier has to still have low noise and distor... (more)	—	over 1 year ago
Answer	—	A: Deriving resistor values for a taper pad attenuator I'm thinking out loud here and haven't solved this yet. This answer is logging my process as I try to solve the problem. It may very well result in the same long-winded process you went thru. Nothing shrewd or insightful is promised. There are three unknowns (R1, R2, R3), and there are fortunat... (more)	—	over 1 year ago
Answer	—	A: pH Electrode Buffer - Offset when solution grounded It seems you have ground loops, and possibly having multiple ground connections shorting out your signals. Your hand-sketched diagram is a good start, but you need to show all the ground connections. The scope is presumably grounded via its ground lug that plugs into the electrical outlet. Let's... (more)	—	over 1 year ago
Answer	—	A: Technique to reset pulse transformer core quickly Note that open-circuiting an inductor "resets" the magnetic field instantly. The downside is that this also generates infinite voltage for that infinitely small time. Infinite voltage is obviously bad, but you should easily be able to tolerate "high enough" voltage relative to your 5 V drive. Us... (more)	—	over 1 year ago
Answer	—	A: Power amplifier for remote controller According to the datasheet that Andy linked to, the chip can be configured for 0 dBm output. With the proper antenna, that is probably good enough for 20 m, but you'll have to test it yourself to know for sure. If your environment is noisy, or there are obstructions causing path loss or multi-path ... (more)	—	over 1 year ago
Answer	—	A: Can confusing the plugs for earphones and microphones do any damage? Yes, plugging a microphone into a headphone output could possibly damage the microphone. Microphones are designed to work on tiny vibrations and tiny currents. A dynamic microphone will work backwards as a speaker, but at very low power. In any case, across all the various combinations of ouputs... (more)	—	over 1 year ago
Answer	—	A: Circuit which create ac sine wave from dc pulsed signal There is no "simple" circuit that does the reverse conversion of what a full wave bridge does on a sine wave. However, it is possible to get there from here. Most of what you are asking about is an inverter. That's the reverse of a DC power supply. You put DC in, and AC power comes out. Put ... (more)	—	over 1 year ago
Answer	—	A: What are the key programming skills for an embedded systems engineer? First, we have to clarify what you really mean by "embedded systems". There are many systems where something that is logically a PC is embedded. There is a whole industry around "single board computers" (SBCs). For a few 100 dollars, you can get a board that runs Windows or Linux, but is inten... (more)	—	almost 2 years ago
Answer	—	A: Op Amp Hartley oscillator You are asking how to analyze this circuit: Forget about what you think it should be called. Before attempting to model specific aspects, first try to understand the circuit. The opamp provides gain of -R2/R1. For an ideal opamp, the output of the opamp has zero impedance in this circuit.... (more)	—	almost 2 years ago
Answer	—	A: Small signal analysis of BJT in saturation region A resistor is not a good model for a saturated BJT. According to your graphs it is, but those are simplified. There isn't really a single slope for all base currents as your graph shows. Even if you can approximate some region of interest with a fixed slope, that slope will vary quite a bit betwee... (more)	—	almost 2 years ago
Answer	—	A: Band pass filter given cutoff frequency and bandwidth I have decided to try design a band-pass filter with a cut-off frequency of 10kHz and bandwidth of 2 Hz. It's "10 kHz", not "10kHz". There needs to be a space between the number and the unit. NIST has a good document about this. Proper use of units and their presentation matter. I've sai... (more)	—	almost 2 years ago
Answer	—	A: Finding voltage gain of Hartley oscillator I'm not going to get into rigorous analysis. My perception is that you're getting hung up on details and forgetting to think what the overall circuit is doing and how it works. I'll therefore stick to providing some intuition. An oscillator is what an AC amplifier becomes whenever there is posit... (more)	—	almost 2 years ago

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