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2

The crystal earpiece has such high impedence that it presents virtually no load to the CD4024. Normal earphones have impedence in the 16 to 32 ohm range, which would (at 9V) cause the CD4024 to provide far more current than it's capable of, potentially damaging or killing it. You need an amplifier with high input impedence which is capable of driving ...

1

In a Buck Converter the inductor ripple current is determined by (approximately): $$\dfrac{V_o.(1-V_o/V_i)}{L.f}$$ Which works out to be 6.66A for your values. Designing the ripple current to be too high results in excessive RMS ripple losses in the inductor, output voltage ripple and bulk capacitor ripple losses (and heating). Too low a value results in a ...

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For the mosfet to work as an amplifier, it needs to be biased in the saturation region, ie Vgs needs to be > Vt (4.15V). And it needs to remain so irrespective of excursions of +/- 100mV of v in.

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You are on the right track. You need a bistable circuit, which halvens the frequency of the photocell signal, and gives high output every other pulse. Besides that, you may want to use a monostable multivibrator to adjust the duty cycle (i.e. the "high" time), in order to get pulses of the right length.

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Very simple problem with an equally simple fix. Your entire circuit is floating. You need to use this for GND: Edit: Node 0 is the internal reference in SPICE for all voltages, and the ground symbol with the graphic '0' is connected to it. Every node in your circuit must have a DC path to node 0 (even if that path is a 100G ohm resistor). The ground ...

2

There are two challenges: Latency USB has two orders of magnitude higher latency than PCI. Many PCI drivers assume memory mapped access to registers on the PCI card with the CPU blocking on the bus transaction. Unmodified PCI drivers over a PCI-over-USB bridge are likely to fail because of wrong latency assumptions. Check this study on PCI latency: PCI ...

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I don't see any reason it isn't doable, but you're taking on quite the project here. There are a lot of layers you'll have to implement to make it successful. Your final solution will probably look something like this: PCI Physical -> PCI controller -> MCU translator -> USB client controller -> USB Host Driver and USB to PCI device emulation I think your ...

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There are numerous problems with your schematic:- The ESP8266 is rated for 3.6V maximum. A 3.6V NiMH battery can charge up to 4.2V or higher and the Schottky diode may drop less than 0.4V, so the ESP8266 could get over 3.8V which will probably destroy it. You should insert a voltage regulator to keep the voltage down to a safe and constant value (eg. ...

2

Since the aesthetics of the enclosure are often what distinguish your product in the marketplace, it is an industrial designer, not an industrial engineer, who should be doing the enclosure design. Your company may have one in-house, or hire one as a consultant. The industrial designer will be working with any other engineers involved in the project, such ...

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Ideally, multiple people would be involved in the case design. In your case, you were worried about grounding. But you might also be concerned about heat dissipation, the strength of the enclosure, ease of manufacturing the case, assembly processes, the cost of the case, safety standards, etc. It would be highly unlikely, even if you work at a small ...

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In this case your boss dictated the terms, and you live with them. The EE should specify whether there are any specs that need to be met by the case, hand it off, and review it prior to production. It's all one team.

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Generally, microcontroller vendors put a range of memory in their devices that is suitable for typical applications. So, if you only need a few I/O pins and one SPI in a small footprint device, you will be unlikely to find anything that ships with 500 kBytes of Flash and 64 kBytes of RAM. With larger devices, which are closer to SoC packages, even the ...

3

If only it were possible to code your embedded system first and then build the hardware. That would make everyone's life easier. Unfortunately, that also means your deadlines are out the window. Typically the hardware has to be designed long before the software is done because hardware parts frequently have long lead times. Thus, embedded sw developers will ...

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Of course, for a single homemade prototype it may be a good recommendation to start with the most powerful of all compatible micros and scale down afterwards. However if you want to win a quote, you have to tell your customer a price before you have the money to implement anything. Therefore, good practice is to write down some kind of specification ...

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Personally for hobby projects I tend to use the most powerful microcontroller in the family with the right footprint. I then develop the PCB, write some code and produce a prototype. This has the advantage that I know the small number of microcontrollers fairly well, so I can rapidly prototype without having to read a whole datasheet. I also have breakout ...

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You should be able to modulate the 400kHz up and down a little bit. This will spread the spectrum of the noise your 6ph converter produces. This would be a standard approach. If you want this verifying for your precise set-up then circuits are needed.

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