Help needed with circuit.

Other Hardware General Electronics
1

Hi Guys

I am having a hard time using an Arduino Uno to control a 0V - 10V Damper actuator.

Below is the link to the specified actuator.

http://www.fmfranklin.com/data/siemens/gdb16-1-glb16-1.pdf

And this is the wiring schematic that I found.

I have the actuator running off a 24V AC transformer and it does drive when manually adjusted so that hopefully rules out any problems with the actuator itself. The transformer output is then converted into DC via a rectifier and associated components. The final output Voltage is 24V DC. I then take that 24V DC and drop it down to 12V DC with a L7812CV (Not the LM7812CV that I have in the image). This 12V DC supplies the Arduino on the Vin & GND pins as well as the Op-amp.

Here is the wiring diagram.

I have managed to generate the 0 -10V DC signal by means of a Filter, Op-amp and a NPN transistor. The output voltage (0 - 10V) are are then sent to the actuator signal wire and it should move.

Do I have to ground the GND of my circuit with the AC 24V that powers the actuator and if so where?

Any help will be appreciated.

Thanks

2

Put a 200uF capacitor on the 24v DC node.
Put a 203uF capacitor on the 12v DC node.
The LM324 op amp has a weak output stage, so it cannot drive (1.5 amps/Hfe) high enough.
Look at the spec for the LM324 output : feeble.

3

Hi AmbiLobe

I understand the need for the capacitors but will this resolve my control problem? (Ordered the 200uF's but they were not supplied)

I have tested the output 0 -10V and it is stable as a signal (Just what I need and it does not drop when connected to the actuator).

Am I missing something?

4

The diagram shows that the reference for signals is the neutral side of the 24V AC supply, so you cannot use the
circuit you propose - you cannot derive the DC from the AC by a full-wave bridge.

Use a 24V AC transformer secondary purely to power the actuator, and a separate 12V DC supply for your op-amp
circuit. Call one end of the 24V AC secondary "neutral" and connect it the the -ve of the 12V supply.

Using 12V DC rather than 10V means you only need an op-amp that handles swings to the negative rail
(much more common than true rail-to-rail op-amps).

5

Hi MarkT

Thanks for the help. Everything seems to be sorted now. :slight_smile: