Turning bb power supply on/off with arduino

Projects Programming
1

hi there,
I have a very basic question, i bought a parallax powerpal bb power supply with a great feature. you can pull a pin low with a microcontroller to turn it off. it says in the manual "VOUT ON/OFF could be controlled by a simple switch, or electronically by driving the ON/OFF signal pin low using a microcontroller. " so i have the signal pin connected to my arduino and have been using an LED in place of the powerpal (mail is soooo slow) and digitalwrite the pin high to turn on the powerpal (LED) and low to turn it off. the LED does what i expect, but the powerpal just stays on. if i ground the PP signal pin it turns off as the manual says it should. i know nothing except it aint working. is writing a pin low the same as grounding it or is it just basically no potential? what should i be doing?

2

Where’s your wiring diagram of the setup ?

3

Hi,
Measue the voltage between the enable pin and gnd of the power supply.
If you measure 5V, then you need a BJT/MOSFET or opto-couple the gnd the enable pin.

A schematic would be great, do you have the gnd of the powersupply connected to the gnd of the Arduino?

Tom... :grinning: :+1: :coffee: :australia:

4

here you go, crude, but i think you get it. i was beginning to wonder if i would need to use another device. i had hoped the powerpal would simplify things.

IMG_0107
IMG_01072048×1536 439 KB

5

so is something like LND150 mosfet the thing? i would like the powerpal to be off by default and only on when i need it to be. so with the mosfet in depletion mode the powerpal control pin is grounded and therefore the unit is off. if i'm understanding this.

6

anybody?

7

Hi,
Have you got a DMM?
If so measure the voltage on the ON/OFF line when it is open circuit and then with the controller trying to turn it OFF.

You may need to have a MOSFET pull the ON/OFF line to gnd.

Tom... :grinning: :+1: :coffee: :australia:

8

nvm found

9

i do have a DVM, but haven't had the time to check. but according to the powerpal instructions, that's what i need to do. so it looks to me like a depletion mode p channel MOSFET or a p channel JFET.

10

Which Arduino? What is the voltage between Arduino GND and PP pin?

11

Hi,

Why... The data sheet says you pull the pin to gnd.
You do this with an N-CH Enhanced MOSFET.

Tom... :grinning: :coffee: :+1: :australia:

12

This is true, but i want off to be the default state of the PP. i only want it on for short periods. So I guess I like to be efficient. Even though we’re only talking about a ridiculously small current, I just don’t like the idea of part of it always on, to keep the other part always off.

13

Hi,
Okay, understand.
Will your servo be able to hold position without any power applied?
Is there torque load on the servo output shaft?

Tom... :grinning: :coffee: :+1: :australia:

14

There is a little load at what would be the off position, but the load is exactly aligned with the servo shaft so no torque. That’s one reason I’m having it turn through 180 deg. So would a p channel JFET be a good option?