Can I attach two transformers in parallel to the same 120 VAC wire. I want to put in a 120VAC to 30VAC and a 120 VAC to 9VDC transformers on the same power cord. Is this safe and will it lower the output voltages or current of either transformer? Would it be best to ground to the neutral or gnd for both or should I do one for each transformer?

Thanks I think you were right about it being too much current. I added a 100 ohm resistor to the 5v pin and it works fine now. What were you guys saying about grounding the Arduino to the external power supply though? I am going to power the Arduino with a 9VDC transformer connected to my 120 VAC wall outlet.

Can I use a higher amperage is I power the Arduino from a battery or other source?

When I use the 5V pin to power a Temp/Humidity sensor the Arduino says COM8 is in use so I can't read the serial, but when I am using the 3.3V pin it works. Problem is I need both for this project so I have to unplug things then unplug the Arduino and mess around and wait a while before I am able to see COM8 as an option again to read from it. My code is pretty simple andI am using the DHT library to read from the sensor which is the RHT03.


I have also had this problem long before I was using the sensor. Anytime I plug something into the 5V of the Arduino my computer makes the babum sound and I have had trouble uploading to the Arduino before because of this COM8 problem that I am pretty sure is associated with using the 5V pin.

I have an UNO and can't use the 5V pint and read from serial on COM8 at the same time? whenever I try to nothing happens with Arduino and the IED says something else is using COM8. Is Arduino able to handle both at the same time or am I doing something wrong?

It is for a centrifuge. I am planning on attaching a plastic disc directly to the motor shaft.

I am working on a project which will need an as small as possible DC motor which will spin up to 2500 RPM with a little bit of weight on it, maybe a pound. I don't know a ton about how to pick out the right motor and will need a speed controller too so that I can control this setup with my Arduino. Thanks.

I have the feedback loop taken care of. My question is more of how much would be a minimum number of watts to maintain the temp and increase it fairly quickly when it drops and on how I can figure out how much power I need / what kind of transformer would be needed to power the elements. I guess I would just like recommendations on what I should use.

Hello I am making a cell incubator which will be made from a styrofoam box and controlled by my Arduino. The inside of the box will have about 1 cubic foot of space and I am thinking about heating it with aluminum clad power resistors attached to a CPU heat sink. I don't know how much heat I am going to need or how many resistors create it to maintain 37 C. Can someone direct me to tutorials or tell me what kind of power I will need and what kind of transformer to get power from an American wall power socket? I have a general idea but I am knew to heating and to anything AC power. I am also very open to other types of heating elements if anyone knows of a better option.

Thanks everyone! I have just finished purchasing almost all of the stuff you recomended.

Thanks and I would like something a little more accurate in temperature because I would like to keep my temp within 1 degree Fahrenheit or better, and those resistors might be a good idea, I was originally planning on attaching the kapton heater to the bottom of a CPU heat sink.

Thanks a lot for all the help so far but I am building a cell incubator for growing mammalian cell cultures, not a chicken incubator.

So I am making an incubator that I want to be able to control with my Arduino Uno. I am thinking about using a heating element and digital thermometer to do his but I don’t really know how to get the high voltages that I will need for powering the element other than that I will need a relay and transformer. I am somewhat new to Arduino and new to using high voltages or anything with AC current. I would also like be able to read and possible control humidity of the air inside the incubator and view everything on a small LED screen, but that is a secondary goal to mainting temp I need. Please tell me or direct me to a good tutorial on how to set up and design the high voltage stuff for a small temperature control system.

I am thinking about using a heating element like this one to do the job. What do you think and what more would I need?
http://www.omega.com/pptst/KHR_KHLV_KH.html