u/Kalex8876

Idk if I’m using the saying correctly but here’s my dilemma.

I do like this company and I applied to a bunch of positions. My recruiter has been extremely helpful and nice with helping me get pushed along for interviews I qualify for.

I had two (I rejected one) Tucson offers. I was able to hold off and keep interviewing for other roles at the company. I have a strong preference to stay in Texas, so that’s where I targeted.

Long story short, it didn’t pan out. They want to send offer for Tucson position.

Now, I am highly conflicted. I don’t want to sour my relationship with the company so I don’t want to renege. However, idk if something more aligned for me can come up.

I also understand clearance process takes a long time, so I would need to start it soon.

I have a few external interviews (other companies) that are in Texas tho maybe the name isn’t as big as this company. Also, I’ve heard this company’s education benefit is hard to beat, and I intend to use the benefit.

Is there a possibility to accept the offer, start the process but if something in Texas comes up, I can switch? The clearance paper work would stay the same right?

Also, I know this job market sucks ass and is down right depressing. I’m tired of it.

What should I do? Any advice please? Thanks.

Idk if I’m using the saying correctly but here’s my dilemma.

I do like RTX and I applied to a bunch of positions. My recruiter has been extremely helpful and nice with helping me get pushed along for interviews I qualify for.

I had two (I rejected one) Tucson offers. I was able to hold off and keep interviewing for other roles at RTX. I have a strong preference to stay in Texas, so that’s where I targeted.

Long story short, it didn’t pan out. They want to send offer for Tucson position.

Now, I am highly conflicted. I don’t want to sour my relationship with RTX so I don’t want to renege. However, idk if something more aligned for me can come up.

I also understand clearance process takes a long time, so I would need to start it soon.

I have a few external interviews (other companies) that are in Texas tho maybe the name isn’t as big as RTX. Also, I’ve seen on this sub that RTX ESP is hard to beat, and I intend to use the benefit.

I also kind of worry about what I’ve heard that even if I make a product off-work off-hours, RTX can still have possession of it? I don’t really understand that. I want to be able to tinker in my lab freely. I won’t do anything on RTX property ofc.

Is there a possibility to accept the offer, start the process but if something in Texas comes up, I can switch? The clearance paper work would stay the same right?

What should I do? Any advice please? Thanks.

Hey guys,

I’ve had interviews recently that I go through the job description to see what topics I might expect when it comes to technical questions and just try to absorb as much info as I can in those topics.

CS has methods and other resources. I’ve seen voltage learning for hardware but it’s not free, I also saw hardwareishard.com has a nice looking page on technical question but for MEs.

This will have to be a collaborative effort. People submitting questions they get during interviews and we just add it in the site. I’m thinking it’s all going to be free / open source, I feel it will just be really helpful imo.

It could have like categories, for eg, for a digital hardware role , the a dropdown of different topics you might expect (still have to look at the job description tho) and you can click in and see notes on the topics, maybe a quiz.

However, if people don’t see the need, that’s fine. I thought of it today and it felt like I’ve seen multiple people suggest similar on Reddit (idk if those were going to be free) but actually going online, the resources are quite fragmented.

Hello all,

I have been using Matlab and simulink since I started college and I really like it, even with little frustrations like connecting simscape and simulink sometimes.

So, recently, I’ve been doing PCB projects and been doing simulations. For example, using LTC4070 or CD4017B, I use LTSpice for these and I so dislike LTSpice. Honestly, it’s made me more appreciative of simulink. It feels unintuitive and janky.

I was just thinking that if simulink allowed blocks that you can just input datasheet parameters, it will be so great.

Or is there a way to do this and I just don’t know? If there is, please share.

Good day all,

I am working on a piezo energy harvester such that a storage element primarily power the load directly, and while it's powering the load, it will also be charged from a piezo cell or array or cells.

I designed this with the idea that the max input voltage will be 30V pk-pk, this was a common value I saw on digikey for piezo cells. I imagine one can connect the cells in parallel to get more current.

Main features:

• Reverse polarity protection
• ESD protection
• Fuel gauge
• Vibration sensor hook up
• Accelerometer
• 3.3V and 5V outputs with max 0.8A
• Can take li-ion, lipo 4.2V battery or around 4V capacitor
• High and Low battery monitor outputs

An example application I can think of off the top of my head is some strapping the battery and module to their leg (with some padding) and have wire going down to their shoe where the vibration sensor (LDT0-028K) and piezo cell(s) are connected. They can connect the module to a MCU like arduino and record data maybe to a SD card or over the air.

I would greatly appreciate hearing any of y'alls idea of what you would do with this if you had it or think of.

Main parts used:

• Accelerometer: MC3479
• Charger: LTC4070
• Rectifier: KBP2005G
• PMOS: BSS84PH6327XTSA2
• TVS (for piezo): CEZ36V,L3F
• TVS (for the rest of the schematic): ESD9X5.0ST5G
• Buck-boost converter: TPS63000
• Ideal diode for reverse polarity of 3.3V and 5V outputs: MAX40200
• Schottky diode for piezo input: SK15
• Fuel gauge: MAX17048
• Vibration sensor: LDT0-028K

The PMOS allows us to increase charge current to 500mA. All resistors are rated 0.5W. Almost all capacitors are ceramic.

My main question is, did I set up the vibration sensor circuit correctly? I have this diode array to clamp the voltage spikes a bit from the vibration sensor before it goes to VCC of a MCU. Someone said I might also need a voltage divider or regulator here?

I'm just very unsure of this setup.

Vibration sensor

I also hope my 470μF capacitor I put after the full bridge rectifier for the piezo is good enough for smoothing out the wave?

Here is the schematic:

LTC4070

3.3V and 5V Outputs

Fuel gauge

Vibration Sensor

Accelerometer

https://preview.redd.it/u4r8hdtwkrzg1.png?width=4096&format=png&auto=webp&s=7bdf33213080793ff047524b42973c5dc58f010b

Full Schematic

Thank you for your time

Good day all,

I am working on a piezo energy harvester such that a storage element primarily power the load directly, and while it's powering the load, it will also be charged from a piezo cell or array or cells.

I designed this with the idea that the max input voltage will be 30V pk-pk, this was a common value I saw on digikey for piezo cells. I imagine one can connect the cells in parallel to get more current.

Main features:

• Reverse polarity protection
• ESD protection
• Fuel gauge
• Vibration sensor hook up
• Accelerometer
• 3.3V and 5V outputs with max 0.8A
• Can take li-ion, lipo 4.2V battery or around 4V capacitor
• High and Low battery monitor outputs

An example application I can think of off the top of my head is some strapping the battery and module to their leg (with some padding) and have wire going down to their shoe where the vibration sensor (LDT0-028K) and piezo cell(s) are connected. They can connect the module to a MCU like arduino and record data maybe to a SD card or over the air.

I would greatly appreciate hearing any of y'alls idea of what you would do with this if you had it or think of.

Main parts used:

• Accelerometer: MC3479
• Charger: LTC4070
• Rectifier: KBP2005G
• PMOS: BSS84PH6327XTSA2
• TVS (for piezo): CEZ36V,L3F
• TVS (for the rest of the schematic): ESD9X5.0ST5G
• Buck-boost converter: TPS63000
• Ideal diode for reverse polarity of 3.3V and 5V outputs: MAX40200
• Schottky diode for piezo input: SK15
• Fuel gauge: MAX17048
• Vibration sensor: LDT0-028K

The PMOS allows us to increase charge current to 500mA. All resistors are rated 0.5W. Almost all capacitors are ceramic.

My main question is, did I set up the vibration sensor circuit correctly? I have this diode array to clamp the voltage spikes a bit from the vibration sensor before it goes to VCC of a MCU. Someone said I might also need a voltage divider or regulator here?

I'm just very unsure of this setup.

Vibration sensor

I also hope my 470μF capacitor I put after the full bridge rectifier for the piezo is good enough for smoothing out the wave?

Here is the schematic:

LTC4070

3.3V and 5V Outputs

Fuel gauge

Vibration Sensor

Accelerometer

https://preview.redd.it/cnh5ku2wjrzg1.png?width=4096&format=png&auto=webp&s=e6e9d2a4dcfb4df339c521e15c413223fc7e2d0c

Full Schematic

Thank you for your time

Good day all,

I am designing a piezo energy harvesting board with some built-in features like a fuel gauge you can connect to a MCU to get readings on the battery.

So, on particular application I can image this being used is: you have the module strapped to your leg (around the calf area) on one side then the battery on the other side or something like that. Then, there are leads that go into the shoe with the piezo cell like this AB2063B-2.

The leads will also likely go to a vibration sensor like LDT0-028K. My thing now is how do I interface with this sensor to have connections to a MCU?

I've seen articles like this or this arduino forum thread saying to use like a 1M - 50MΩ depending on frequency. From google, frequency of someone running or jogging is like 2 - 3 Hz?

From the Arduino thread, that implies needing like 20MΩ for the load. But the commenter also mentioned using a force sense resistor if you want to measure pressure or bend ratio. So, I looked it up and the force sense resistors look like the vibration sensors or piezo sense transducers so I don't really understand where it is meant to go.

Also, after the load resistor, what connections do you need for the MCU? An analog pin and GND? Does it matter which is which?

Like this?

Genuinely.

I got feedback today that I don’t have much experience with some of the things the role entails so they rejected me. This was an entry level role and they had no yoe (no minimum anyways) requirement.

I don’t really get it. The skills they are talking about I am actively working on, on my own time with personal projects and I told them as such. I really wanted this role but I just feel numb now.

As a side note: I’ve done multiple internships, they just weren’t in the same field as this particular role. I’ve tried to supplement that with personal projects.