# Boosting the Amper and altering the frequency

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,758
some outputs show 0.2-0.8V when the pin is off. It should show 0V.
That's probably totally o.k. The Arduino'S GPIO pins are logic level outputs and a logic low for CMOS is generally defined to be any voltage between 0% and 30 % of VDD, i.e. 0 V ... 1.5 V at VDD = 5 V (see also here specifically for Arduino).
The exact voltage depends on the load current through the GPIO pin. The higher the current, the higher the voltage. If you need high current and low voltage, you need to insert a driver circuit between the Arduino and the load. See e.g. here for examples.

#### Maxouishere

Dec 29, 2021
78
Hello there
Pardon the intrusion, it seems you are in more than capable hands. Excellent thread.
I just have to ask .What do you do with the bee venom?
HelloI am doing beekeeping as a hobby (currently 5 hive) and I am making ointment with venom for personal use.
THat'S probably totally o.k. The Arduino'S GPIO pins are logic level outputs and a logic low for CMOS is generally defined to be any voltage between 0% and 30 % of VDD, i.e.. 0 V ... 1.5 V at VDD = 5 V (see also here specifically for Arduino).
The exact voltage depends on the load current through the GPIO pin. The higher the current, the higher the voltage. If you need high current and low voltage, you need to insert a driver circuit between the Arduino and the load. See e.g. here for examples.
Thanks. Current is fine. Only problem(?) is non zero voltage when off. I thought it was a problem because 4 outputs show 0V when off and only one of them shows 0.8V now. Can it be a problem due to wiring order? Yesterday It was the same problem with my 1 output demo system where I test components. Then I changed the random wiring order like the image below (breadboard) It then showed 0V when off.

Wiring order matters? If so, let's say for 3 outputs, image below is OK?

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,758
Current is fine.
What do you mean by that?
Only problem(?) is non zero voltage when off.
No, not a problem. As soon as you start drawing current from a logic chip's output, the voltage rises above 0 V (for low level) or goes below Vcc (for high level). This is due to the finite output resistance of the chip. THis is why you need a driver for higher output currents.

Your images I don't understand. I see only black boxes with text. Please provide a schematic drawing.

#### Maxouishere

Dec 29, 2021
78
What do you mean by that?

No, not a problem. As soon as you start drawing current from a logic chip's output, the voltage rises above 0 V (for low level) or goes below Vcc (for high level). This is due to the finite output resistance of the chip. THis is why you need a driver for higher output currents.

Your images I don't understand. I see only black boxes with text. Please provide a schematic drawing.
OK. Same schematic in this post but without any diodes. I will draw the updated schematic and share. But there is a strange occurance. In morning, I measured it 0V when off. And now in evening, I measured again. I measure some outputs as 0.1-0.3V when off. And I am almost sure tomorrow morning I will measure it as 0V when off. Residual voltage or faulty multimeter, I think.

#### davenn

Moderator
Sep 5, 2009
14,271
Your images I don't understand. I see only black boxes with text. Please provide a schematic drawing.

likewise, only black boxes with text across top and bottom

#### Delta Prime

Jul 29, 2020
2,033
I am making ointment with venom for personal use.
Use your powers for good not evil.

#### Maxouishere

Dec 29, 2021
78
I tried to draw the schematic with breadboard. Same transistor-resistor-voltage_regulator setup is also applied to pin,3,4,5 and 6. So that means 5 outputs total. I didn't add them on the image below because it becomes too complicated to draw.

Now I measured again the voltage at the end of the blue lines. I made 2x setup with 5 outputs each just to see if they differ. On first setup, one output is measured 350mV when pin is set to LOW and other four are measured 0V when set to LOW. On the second setup all five outputs are measured 150-250mV when set to LOW. (But 24hr ago all of them were 0V when off.) I also measured the voltage from the arduino pins directly, It drops to 0V when set to LOW. And bases of both transistors voltage also drop to 0V when set to LOW and around 1.8V when set to HIGH. If it is not related to wiring order (for example at above image, for negative terminal it is connected from right to left, -12v,-in,-out,arduino_gnd,bd135_gnd), I suspect it is something to do with the voltage regulators' internal circuitry.

#### Maxouishere

Dec 29, 2021
78
@Harald Kapp I built one more, on this one when Arduino's pins set to low, 4 of them show 6.8V, one shows 12.2V. Please check my above schematic and tell me what I am doing wrong. I couldn't figure it out.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,758
It's an effort to decipher a circuit from the wiring, especially as the symbols for BC107 and BD135 don't match the physical appearance of these components.
It will be much easier for us when you present your circuit as a schematic diagram.
Also, in case you can't draw a schematic as requested, at least use red for positive supply wires, blue for negative supply wires (gnd), otehr colors for signals. Also label any signal/wire that you reference in your text. It is much easier for us to follw e.g. a signal named "output" than to fin a signal that "connects to the collector of the second NPN transistor" - just an example).

For the time being: check the correct placement and assignment of the transistors and their pins (E, B, C).

Now I measured again the voltage at the end of the blue lines.
Please be more specific. Ideally mark the measuring points in the diagram with lables and reference these lables in your text. The blue wire (in fact any wire) has 2 ends. Which one do you mean?

when Arduino's pins set to low, 4 of them show 6.8V, one shows 12.2V.
12 V on an Arduino output? Your poor microcontroller sure is fried. Check your zener diode, is it correctly oriented (cathode to +12 V)? Check your ground connections.

#### Maxouishere

Dec 29, 2021
78
@Harald Kapp I find the problem, transistors are fried due to reverse connection of +in and-in. (mistake )

In your post you said i need a driver. Does my current setup (only difference is 138 ohm res value is increased and is conencted to 12V, and same setup for 5 pins) is OK? I don't want high current. Only high voltage (around 30V). Is it OK, if I leave it like that?

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,758
The transistors are the driver.

#### Maxouishere

Dec 29, 2021
78
Ohh. I thought I should have to add a diode like in the link. Alright then, It looks fine.

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