Power supply (battery, USB)

[reiner_doll]

For an educational project, i need a way to supply arduino in different ways. Students will connect usb, or/and supply the board with 4 NICD-accumulators (4.8V) or simple "one-way" batteries (4x1.5 = 6 V).

Switches are no solution, they will switch them incorrect

Any ideas ?

[sterretje]

Which Arduino?

Please explain in more detail what your problem is.

To prevent multiple switches being on at the same time, consider a 3-position switch so one can only use one position at a time; a 3-deck 3-position rotary switch comes to mind.

@reiner_doll

4 NICD-accumulators (4.8V)

Going to 5V?

@reiner_doll

simple "one-way" batteries (4x1.5 = 6 V)

Check the specs of the Arduino board that you're using. You can not feed that into the 5V pin.

[reiner_doll]

Very strange possibility:

Shifting battery power from 4.8 (accu) or 6 (battery) up to 8V with a little up-switching regulator. Then to Vin on Arduino Uno.
The FET on Arduino will prevent damage, it switches between USB and output of the on-board regulator 7805.

Not very economic, but fool-proof !

[LarryD]

@reiner_doll

Shifting battery power from 4.8 (accu) or 6 (battery) up to 8V with a little up-switching regulator. Then to Vin on Arduino Uno.

• Use a BOOST/BUCK converter (a bit more flexible), feed 7v into Vin.

• For students, replace the potentiometer with 2 resistors to get 7V.

---

---

---

• However, these MT3608 Boost converters are good too.
  Select resistors for 7v out going to Vin on Arduino.

Share tips you have come across

In situations where an accidental change in a potentiometer setting can cause catastrophic problems, change the potentiometer out for fixed resistors. Make a resistor substitution board ahead of time to use it to determine what the values of these resistors should be. All the standard resistor values (SMD 1026) have been placed on the substitution PCB. One end of all the resistors are common and would represent the wiper on a potentiometer. Female headers on the other side of the resistors w…

Share tips you have come across

Further to post #730. Replacing a potentiometer with two SMD resistors has been covered earlier in this thread. Now we are using machine pin headers to raise the SMD resistors above the board rather than mounting them on Kapton tape. Use 3 header pins with the top pins cut off flush to the surface. Solder the 3 pins at the old potentiometer location. As before, after measuring the potentiometer setting, select ‘actual’ standard SMD resistors and confirm they will work in place of the pot. …

[reiner_doll]

thanks a lot for the very infomative answer.
i've done it the same way : a switching up-regulator on vin at 7 volt, and everything works fine. the poti on regulator is no problem, i will mount the regulator on backside of the boards.