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Activity for TonyStewart‭

Type On... Excerpt Status Date
Edit Post #291315 Initial revision 5 days ago
Answer A: Control logic for mosfet in piezoelectric energy harvesting circuit
Every real part has resistance including your piezo current source. Every switch resistance is a loss in energy (I^2 R t)=E and includes diode and transistor switches. What you need, I think, is to incorporate MPT theory into your block diagram and use a goal of matched impedances to achieve it. ...
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5 days ago
Comment Post #290874 FR-4 and soldermask will slowly absorb moisture under pressure. https://www.nextpcb.com/blog/waterproof-pcb--nextpcb
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about 2 months ago
Comment Post #290595 When I did Hipot testing, I modified the tester with a string of resistors to current limit and prevent destructive failures yet trigger insulation failures in the 100uA test. When I tested 5 MVA transformers to 200kV, I used an AM radio and LeCroy scope to measure partial discharge (PD) events befo...
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3 months ago
Comment Post #290595 "When should a transformer core be potted?" >When being attacked by environmental stress from all sides. "Should it be potted at all? " > It is not mandatory. Consider if Dk affected the frequency applied or the thermal temperature from insulation. This may not be in your case, but just ...
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3 months ago
Edit Post #290722 Post edited:
3 months ago
Edit Post #290722 Post edited:
3 months ago
Edit Post #290722 Post edited:
3 months ago
Edit Post #290722 Post edited:
3 months ago
Edit Post #290722 Post edited:
3 months ago
Edit Post #290722 Post edited:
3 months ago
Edit Post #290722 Initial revision 3 months ago
Answer A: estimation of pogo pin resistance
I agree with Olin that unknown contact area is the biggest variable. I think the scientific way is to test and verify each contact using a 4 pin kelvin bridge. The sum of 2 pins carrying constant current can be measured as voltage by 2 adjacent pins on pads sufficiently large. It probably wo...
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3 months ago
Edit Post #290720 Post edited:
3 months ago
Comment Post #290720 My assumptions were based on analyzing the photo of the transparent substrate that the membrane switches were bonded to without any conductive traces. Yet on the same side below them was the carbon printed traces connecting the domed membranes beneath the clear substrate. It is true that membrane sw...
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3 months ago
Edit Post #290720 Initial revision 3 months ago
Answer A: What type of button is this on a remote control
It is interesting to see how they deposited these carbon electrodes over solder mask and copper traces both under the button foil switches and membrane switches alike which offer more tactile feel. Both offer capacitance changes to non-conductive switches. The membrane switches are mounted on their...
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3 months ago
Comment Post #290448 Can you measure or compute the L & C values? https://www.ti.com/seclit/ml/slup376/slup376.pdf
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4 months ago
Edit Post #290424 Post edited:
4 months ago
Edit Post #290424 Post edited:
4 months ago
Edit Post #290424 Post edited:
4 months ago
Edit Post #290424 Initial revision 4 months ago
Answer A: Can I make an AC inductor (reactor) rated 75mH 40A from a 3-phase induction motor?
The 70.9/40.8 A rating for L.R. is rated only for ; Locked rotor time 19s (cold) 11s (hot) I doubt this meets your requirements unless you modify from a forced air cooling motor to a pumped liquid cooling system. I'd contact a local oil-filled transformer supplier and get an autotransformer. ...
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4 months ago
Comment Post #290354 Charge pumps suffer from high very impedance output impedance leakage issues and are not worth the effort. Murata package is my best recommendation. https://www.digikey.ca/en/products/detail/murata-power-solutions-inc/NMV0512DC/5799183
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4 months ago
Edit Post #290423 Initial revision 4 months ago
Answer A: CAN BUS monitoring with a LED
You'll need a differential comparator, something like what was suggested in here. Imagealttext But I'd look for a proper Canbus Rx and extract that to convert to single ended one shot to pulse for activity.
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4 months ago
Edit Post #290341 Initial revision 5 months ago
Answer A: Ceramic capacitor "memory" effect?
I have never seen this slow drift in ceramic caps, yet I have seen fast memory effect drift in S&H designs using high Dk ceramic capacitors in the 70's. So I have learnt that all ceramic caps have memory effects (except low Dk C0G/NP0's). The capacitance also changes with DC voltage, so Ic= VdC/dt +...
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5 months ago
Edit Post #290339 Post edited:
5 months ago
Edit Post #290339 Initial revision 5 months ago
Answer A: What fabrication process is being used for jellybean parts
As of the early 2020s, common technology nodes for SSI (Small-Scale Integration) and MSI (Medium-Scale Integration) ICs include nodes such as 180nm, 130nm, 90nm, 65nm, 45nm, and 28nm. Each technology node represents a specific level of lithographic resolution that costs billions to create. Migrating...
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5 months ago
Edit Post #289916 Post edited:
7 months ago
Edit Post #289916 Post edited:
7 months ago
Edit Post #289916 Initial revision 7 months ago
Answer A: Driving LED with NPN transistor from I/O pin
If you choose suitable ultrabright LEDs , there is no need to use 40 mA. I have over 10 thousand LEDs all over 16,000 mcd at 20 mA which is painfully bright for close indicator but works well 100 m away. They are also all matched brightness and Vf within 10%, but I ordered these special for a high ...
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7 months ago
Edit Post #289915 Initial revision 7 months ago
Answer A: derating MLCC ripple current for transient current spikes
Remember that RMS measurements assume at least 1 cycle or in your case 100 ms or 10 Hz. So the Ripple Current/rms vs Temp rise is always valid for any duty cycle. This means in theory you can raise the current significantly since the spike is a very low duty cycle. In practice, the device will have...
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7 months ago
Edit Post #289904 Initial revision 7 months ago
Answer A: Will shorting a lithium ion battery cause an explosion?
> Will shorting a lithium ion battery cause an explosion? Chain Reaction: The release of flammable gases can lead to a chain reaction, where the heat generated by the short circuit causes even more heat, which in turn generates more gases. This cycle continues to escalate the temperature and press...
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7 months ago
Edit Post #289553 Initial revision 8 months ago
Answer A: Why 3.3V instead of 3V?
The other answers are excellent justification to the the industry standards imposed on CMOS logic. The historical migration to smaller lithography CMOS led to lower Cds values which led to faster rise times or higher toggle f's. However realize that the standard has been undocumented standards of 50...
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8 months ago
Edit Post #289550 Post edited:
8 months ago
Edit Post #289550 Initial revision 8 months ago
Answer A: What is Ground Electrode in EMG?
CMRR design is key to rejecting grid e-fields that impose noise onto EMG, EKG,EEG amplifiers. This includes all series Zs of cable balance and Amp CMRR. For this reason >100 dB CMRR are required using INA's and not OA's with 1% R's (-40dB error). The same CMRR matching is required on 60/50 Hz...
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8 months ago
Edit Post #289549 Initial revision 8 months ago
Answer A: Essential safety features of an EMG/medical grade device?
Current limiting input differential Rs of 1M into a 10M INA with clamp diodes make this a simple task.
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8 months ago
Comment Post #287196 I have successfully solved your problem in the past using a spreadsheet to to determine all the correct values for a potentiometer to give the the desired s21 response from 5% to 100% of the pot value chosen. I trust you can easily do the same. Anectdotal __________ In my case I wanted to d...
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8 months ago
Edit Post #289548 Initial revision 8 months ago
Answer A: Power switches and automotive load dump, unclamped
The spec 79V 0.5 ohm 5ms = 62.41 Joules . The TVS must be rated for a low temp. rise at this energy dump or higher. MOV's are limited by the number of discharges as the oxide wears out, but may be used if size appropriately for desired MTBF.
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8 months ago
Edit Post #289547 Post edited:
8 months ago