Hi! Im new here, and not a lot of time with arduino and electronics.
I have to drive a gauge, which is the receiver in the following diagram:
So, I have to generate the signals needed with Arduino. I have to simulate the left part of the diagram.
The gauge says 24v. I need 3 outs from 0 to 24v.
I thought it was easy with 3 transistors, but I cant get it work. I have try with npn and pnp transistors. I can see with multimeter 0 to 24v for each output, but i dont see any voltaje between them. I supose the transistors cuts it off.
It works with direct 3 pwm 5v signals with arduino. (not, perfect, because it needs 24v to get enough torque). It is only 10mah current at 5v.
But it doesnt work when I try to convert to 24v with transistors.
It's not that straightforward with just a few transistors as you have to reverse the current, which means you have to construct three H-bridges (these also come conveniently in a single package).
8.1 DC synchro
The DC synchro consists of a transmitter and receiver as illustrated in FIG. 28. The transmitter is wire-wound circular resistance with three pick offs. The input shaft (of the device being monitored) is attached to the two contacts that slide across the resistance windings. These contacts are insulated from each other and connected to the power supply. The receiver contains a permanent magnet attached to a shaft; the magnet is positioned within three stator windings. DC synchros are known by various trade names including Selsyn and Desyn.
With the two contacts in the positions shown in Fig. 28 , the power supply current enters the resistor at point A, current flows into the top coil (A) of the receiver and splits into the lower coils (B and C). This current sets up three magnetic fields around each of the three coils; the permanent magnet in the receiver takes up a position that aligns with the resulting magnetic field. A pointer attached to the receiver shaft moves to a position inside the indicator. When the input shaft of the transmitter is rotated, the contacts move to a new position. This alters the balance of currents through the resistance windings resulting in a change of currents in the receiver coils. The resulting magnetic flux rotates and the permanent magnet aligns to the new direction, moving the pointer to a different position. Key maintenance point
The DC synchro suffers from contact wear on the resistance windings; this can lead to spurious operation.
An Arduino solution would help.
Is this for an active aircraft, or a simulator..
Tom..
TomGeorge:
Is this for an active aircraft, or a simulator..
Tom..
Hi! thanks
It is for a simulator I am building
Here is a link with this gauge working at 5v.
It is simulating:
no voltage ( needle left)
up position
3 down positions
It works quite well with 3 direct outputs 5v pwm (really one of them is always ground, because needle returns to left with a spring). And I think this is no dangerous, as I measue maximun 10mah per pin. But I would like to use it 24v and the correct equations.
Are 3 h-bridges needed? I dont need to change polarity, only from 0 to 24v in each pin.
That is, I need exactly the same beaviour of 3 arduino pwm outputs, but 24v.
