FROG Muscle Project - How to Use PWM with Step-Up or Transistor to Make 9V

Hi. I am building a circuit for a frog muscle project. Basically, in the project I am using Arduino UNO to shock a Frog Muscle, and while the muscle is contracting, it will move a propeller that will power a small boat. (Biomedical Project).

On Arduino, I am using pin 9 (PWM) and Ground - those are connected to 2 ends of a frog muscle. The voltage across the muscle is about 4.5 V. I would like to boost up the voltage up to 9V. I was thinking about XL6009 Steep-up Boost or a transistor. However, I am not sure how to connect it to Arduino, and if it would work with Arduino using PWM.
Btw. Arduino is powered by a 9V battery.

Some guidance and opinions will be greatly appreciated.

Thank you.

(sorry I am a newbie with Arduino and Electronics)

are you talking real frog legs or is a product with this name?

Real frog legs… Frogs freshly killed and dissected…

mrmrmrpl:
Real frog legs.. Frogs freshly killed and dissected...

Sounds grotesquely maccabre.

It's a biomedical project... sounds like sounds... but actually the muscle contraction is powering boat really well.. the problem is i don't know how to boost up voltage from 4.5V to at least 9V using PWM.

mrmrmrpl:
It's a biomedical project... sounds like sounds... but actually the muscle contraction is powering boat really well.. the problem is i don't know how to boost up voltage from 4.5V to at least 9V using PWM.

I am well aware it is a "biomedical" project.

It never fails to amaze me the grotesque experiments humans are capable of conjuring up in the name of "science".

Don't blame me. It's a part of the school's program.. Im a senior.. so no choice.. I am not a fan of killing animals in the name of science.. but there is nothing else I can do besides finishing the project.

You can use an NPN transistor or N-channel MOSFET as a low-side switch for a 9V (or even higher) supply. The power supply positive side goes to the + side of the muscle. The - side of the muscle goes to Collector/Drain of the transistor/MOSFET. The Emitter/Source of the transistor/MOSFET goes to Arduino Ground and power supply negative side. The Arduino pin goes through a roughly 200 Ohm resistor to the Base/Gate of the transistor/MOSFET.

johnwasser:
You can use an NPN transistor or N-channel MOSFET as a low-side switch for a 9V (or even higher) supply. The power supply positive side goes to the + side of the muscle. The - side of the muscle goes to Collector/Drain of the transistor/MOSFET. The Emitter/Source of the transistor/MOSFET goes to Arduino Ground and power supply negative side. The Arduino pin goes through a roughly 200 Ohm resistor to the Base/Gate of the transistor/MOSFET.

Thank you so much! This is very helpful.

johnwasser:
You can use an NPN transistor or N-channel MOSFET as a low-side switch for a 9V (or even higher) supply. The power supply positive side goes to the + side of the muscle. The - side of the muscle goes to Collector/Drain of the transistor/MOSFET. The Emitter/Source of the transistor/MOSFET goes to Arduino Ground and power supply negative side. The Arduino pin goes through a roughly 200 Ohm resistor to the Base/Gate of the transistor/MOSFET.

Do you know if DC-DC Converter, such as XL6009 would work too?

Thank you!

no it wont. That's for boosting supply power not arduino pin output. Seek a tutorial on using arduino and transistors for higher power output.

Hope you have a voltmeter to debug this instead of keep cutting frog legs every time something doesn't work

You made it clear! Thank you.

I really appreciate your help.

Won't hurt frogs too much.. promise :wink:

Could you guys please check if this is right? I use LED as muscle.

One more question.. Can I use the same battery for powering arduino and as power supply for transistor?

Thank you.

That looks accurate to me. Make sure your voltmeter and ammeter are set for AC voltage and AC current since you are using PWM, not DC.

I think that almost any small-signal NPN transistor should work since your voltages and currents are relatively low. The Arduino pin can easily put out 20 mA and even with a transistor with a DC current gain (a.k.a. 'Beta') of only 10 you'd still be able to switch 200 mA. Many basic transistors have a gain of 100 or more.

mrmrmrpl:
Won't hurt frogs too much.. promise :wink:

What's too much? You've already killed them. I'd call that the maximum hurt.

There will be more of this type of thing in your future. Don't think it is the last since you are in this field.

Follow up with the project. :slight_smile: In this case 555 timer and frog legs :wink: