Power source buffer 5V device

$15-25 USD / hour

В роботі

Опублікований

about 9 years ago

$15-25 USD / hour

I'm buliding a product based on Raspberry Pi. I've modified the OS/Software so that it survives sudden shutdowns (power outages) and do not destroy the SD-card (read-only mounting). At some points I'd like to write to the SD-card and be certain NOT be out of power for those couple of seconds. The idea is this: Buffer power in supercaps from a 12V source (AC/DC converter). Use a DC/DC Buck-converter to get to 5V for about 1-2A to feed the Raspberry computer and pheriphals. What I'd like is a 3V signal (3.3 to be exact) on a gpio so that the software can detect if there is power on the supercaps or not (= we can afford to do a disk-write without risk). I've done a basic design using a 78M05ABV but it gets really hot and I'm not sure I draw power in a safe way (overloading the caps, drawing too much from the source, starting the pi with 2-3V (too low)). Also I think the RPI should not boot until we have full caps. I assume you know lots of small voltage electronics and capacitors, ESR, ceramic, electrolyt, etc. to design this for me (virtual breadboard or schematic) so that I can build and test it. I would like to find someone interested in helping me work on this on an hourly basis and make a great design for my product. It will be an iterative approach since I think there will be upcoming modifications and I need a technical sounding board that can help me with the hardware part and avoid dangerous solutions. See attached images as food for thoughts and indications only, they probably do not work (or at least burned a couple of things here)

Electrical Engineering

ID проекту: 7011378

Про проект

8 пропозицій(-ї)

Дистанційний проект

Активність 9 yrs ago

Хочете заробити?

Переваги подання заявок на Freelancer

Вкажіть свій бюджет та терміни

Отримайте гроші за свою роботу

Опишіть свою пропозицію

Реєстрація та подання заявок у проекти є безкоштовними

8 фрілансерів(-и) готові виконати цю роботу у середньому за $20 USD/год.

@pcbdcs

Hello, I have been associated with Hardware design (Circuit / Electronics design), PCB design, PCB Manufacturing, Component procurement, PCB Assembling and Functional testing for over 7 years. I have used various CAD/EDA tools for PCB design. Would you prefer any specific EDA tool for PCB design (or) any tool is okay? I will provide the PCB Manufacturing, Component procurement, PCB Assembling & Functional testing services too. Thanks & Regards, Karthik

$20 USD за 5 дні(-в)

4,8

(126 відгуки(-ів))

6,7

@shahbaz1980

Hi there, My name is Raja Shahbaz Ali, Iam running an R&D Lab. we can assist you in designing and developing the required circuit. The problem can be solved by introducing a backup power source like UPS (un interrupted Power supply). Please feel free to contact. Best Regards, Shahbaz.

$27 USD за 10 дні(-в)

4,6

(58 відгуки(-ів))

7,0

@cscinstructor

I have read and understand your requirements Please open chat window to discuss further.. ++++++++++++++++++++========================+++++++++++++++++++++++++++++++++++++++++

$20 USD за 3 дні(-в)

4,5

(33 відгуки(-ів))

5,2

@pranavsharma2504

Hi there! I'm Pranav, from India.... I just read your project description, and went through the attached image. The first thing that struck me about the attached circuit was, the op-amp is going to send in 5V to GPIO11, which isn't exactly a great thing to do as they are designed to be only 3V3 tolerant. I guess using a simple resistor divider, or 2 diodes in series at the output can give you the desired result, without stressing the Raspberry Pi. The other thought I had was that maybe you'd be better off putting capacitors in parallel. instead of series. This is so, because as capacitors age, (or even when they are new) their topping voltage would be the same, but the capacity might be a little different. In a series circuit, when the capacity of the lowest capacity capacitor would be affective. In parallel, since the voltage is more or less the same, this would not be a problem, and each capacitor will drain to the full of its capacity. Regarding the 78M05 getting hot, it is pretty simple, it's bringing down 12V to 5V, that's 7V, multiplied by maybe 0.5A? At least 3W or so, wasted as heat. Using a Buck converter will definitely be a great thing to do. Depending upon the usage and space constraints, you could choose between LM2596, MP2307, or one of the many others... Let's talk about it. And about my credibility, I am a reputed component selector, Schematic designer, and PCB layout and routing expert. Waiting for your message. With warm regards, Pranav

$15 USD за 10 дні(-в)

5,0

(15 відгуки(-ів))

4,8

@bfouli

I have a PhD in Switched power supply and Power inverter design. I have 14 years engineering experience with: 1- Raspberry Pi and ready to program ARM boards via both JTAG and USB together with OpenOCD. 2- High current high precision power inverters and converts DC-DC, DC-AC, AC-AC & AC-DC. 3- Power interfacing and power control using IGBTs, thyristors and high current passive and active components. Also I have several intellectual property achievements including 3 PCT applications WO2006010973, WO/2006/120497 & WO2006079874, an EPO application 05753684.9 and I have a US patent 7480169.

$22 USD за 40 дні(-в)

5,0

(3 відгуки(-ів))

3,5

@MEGiZA2018

Bir öneri henüz sağlanmadı

$16 USD за 20 дні(-в)

4,2

(9 відгуки(-ів))

3,4

@engrnhelectro

i have hand on these type of circuits, i can give you this circuit in 24 hour, it will work like as your requirement.

$20 USD за 5 дні(-в)

4,9

(2 відгуки(-ів))

0,6

@tim42Engineering

I just finished a design for a military product that successfully used supercapacitors in this exact situation. I have a fully tested unit and can provide a design solution for your supercapacitor backup with about 2 hours of work. The method used will very easily provide you your intended IO that will inform you that power has failed and you are on backup power if you start a timer when this event occurs you can use this as your "Last chance to write" signal... I also have quick spreadsheets already written to find out the run time of various super capacitors. I have contacts to make relatively inexpensive circuit boards. I also have the ability to reflow small runs of surface mount parts. Tim

$22 USD за 2 дні(-в)