I am working on building a microscope using 3D printed parts and inexpensive optics. The microscope itself is complete, looks and functions great.
However I need a heated stage for viewing micro organism growth over extended periods of time. I decided on a peltier device sandwiched between 2 pieces of aluminum. I went with a peltier device as it has a uniform heating surface, is very compact, and because there are models with a hole in the middle. It MUST have a hole in the middle so that light can pass through the slide. The temperature on the stage MUST be between 32-34 degrees Celsius. I am working on building a small temperature controller for it which I am kind of struggling with.
For the temperature controller I am using 2 linear regulators in series, one with fixed resistor values to supply a consistent input voltage to the second regulator. The second regulator is connected to a thermistor that is mounted on one of the pieces of aluminum. I tried building it with only one regulator but couldn't get a consistent voltage out, The voltage out changed depending on input voltage. The peltier only needs 1.2V at .39A to reach 33 degrees celsius. The regulator output must be above 1.25V or it shuts off so I decided to build it with a 2.0V output and then use a 2.2ohm 5 watt resistor to step down down the power. This is looking more and more to not be the most ideal setup.
My question is: Does anyone have a better idea? I'm getting annoyed continuously playing with this thing and not making any head room. Has anyone else built a hot side peltier temp controller or have any ideas how to?
Help would be VERY appreciated. Thanks
However I need a heated stage for viewing micro organism growth over extended periods of time. I decided on a peltier device sandwiched between 2 pieces of aluminum. I went with a peltier device as it has a uniform heating surface, is very compact, and because there are models with a hole in the middle. It MUST have a hole in the middle so that light can pass through the slide. The temperature on the stage MUST be between 32-34 degrees Celsius. I am working on building a small temperature controller for it which I am kind of struggling with.
For the temperature controller I am using 2 linear regulators in series, one with fixed resistor values to supply a consistent input voltage to the second regulator. The second regulator is connected to a thermistor that is mounted on one of the pieces of aluminum. I tried building it with only one regulator but couldn't get a consistent voltage out, The voltage out changed depending on input voltage. The peltier only needs 1.2V at .39A to reach 33 degrees celsius. The regulator output must be above 1.25V or it shuts off so I decided to build it with a 2.0V output and then use a 2.2ohm 5 watt resistor to step down down the power. This is looking more and more to not be the most ideal setup.
My question is: Does anyone have a better idea? I'm getting annoyed continuously playing with this thing and not making any head room. Has anyone else built a hot side peltier temp controller or have any ideas how to?
Help would be VERY appreciated. Thanks