Circuit to show power output

[duffin89]

I'm currently designing a setup to show renewable energy in action to school children, water wheel, wind turbine etc for a local ecology centre I help out at.

What I'm struggling with is how to show the output power of the devices in a nice looking way rather than just a wattmeter.

What I would love to have is a circuit that lights up a series of LEDs at different power levels, problem is I have no idea how to do this. Anybody have any ideas?

Thank you for any help

 

[Reloadron]

Personally I prefer a power meter, however, if something along the lines of a LED bargraph indication is what you want I would suggest that you give this link a read. The LM3914 or LM3915 would give you what I think you are after. Keep in mind this is merely a suggestion that would likely need a few other parts tossed in to drive the LED chip. If you look at the chips mentioned you will see what amounts to a stack of comparators in a single chip. The LM3914 being linear while the LM3915 is non-linear (Logarithmic) in response. The reason is covered in the link.

Ron

 

[JimB]

show renewable energy in action to school children

How old are they?

show the output power of the devices in a nice looking way rather than just a wattmeter

One thing which comes to my mind is to explain the important differences between voltage, current, power and energy.
A simple line of LEDs does not necessarily do that.
Maybe if the "renewable energy device" being demonstrated could actually do some work, such as drive a motor/pump and move some water from one vessel to another.
That, to my way of thinking, would demonstrate Energy (the quantity of fluid moved), and Power (how fast it was moved).

JimB

 

[unclejed613]

you could have 3 rows of LEDs, one for voltage, one for current, and one for power. you would need a multiplier circuit for the third row. a simple 2 quadrant multiplier would work here.

 

[duffin89]

Thanks for the replies. The aimed age range is 11-15 so it needs to be simple enough for late primary school aged children to understand.

We are going to have a few things that run off the the devices, I hadn't actually though of having a pump included. Would be a nice way to explain how commercial hydro schemes work by using it to pump water into storage for water wheel. I would love to have more things in with the display but there's limited room in the van that will be used for transporting everything.

I have to say I do like the idea of having 3 rows of LEDs, means it can be used to teach a few different things rather than just simply the power out of circuit.

Just for extra info we are building a water wheel, mini wind turbine and a solar panel to show different types of renewables. As its being used in Scotland we are going to have a 50W Halogen and also a fan of some sort to use with turbine and solar panel. Luckily we are going to be able to charge up a car battery that these will run off from a solar panel mounted to the roof of the van that's going to transport all the kit. For those interested the display will be part of a road show being put together by https://www.theecologycentre.org/

Thanks again for the help.