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1  Using Arduino / Project Guidance / Shrinking high side switch? on: February 03, 2013, 07:04:17 am
I am controlling a VFD (display) from my Arduino. I have a 12V external power supply for the display. For each pin in the display (More than 24) I have a high side switch similar to the schematic below (I don't have R4 & R3 in my circuit). I control the switches from bit shift registers:



For each pin/switch I need 4 components. It takes up a lot of space. How could I go about shrinking the circuit? Any ICs available? Arrays of transistors? Clever ideas?

Schematic above is from:
http://www.w9xt.com/page_microdesign_pt12_hv_pnp_switching.html

Regards,
Tobias
2  Using Arduino / Displays / Re: Controling segment on VFD display with transistor not working? (Newbie) on: January 28, 2013, 06:21:35 pm
Thank you for the links. I'm now much wiser, and will do as you proposed in your first reply.

Your help is much appreciated.

Tobias
3  Using Arduino / Displays / Re: Controling segment on VFD display with transistor not working? (Newbie) on: January 26, 2013, 11:18:24 am
Hello John.

Thank you for your reply (Which I'm slowly digesting).

How is my setup fundamentally diferent to a (common it seems to me) scenario, where one would control a 12V motor with a single NPN like this example:
http://www.jeremyblum.com/2011/01/31/arduino-tutorial-5-motors-and-transistors?

Thank you,
Tobias
4  Using Arduino / Displays / Controling segment on VFD display with transistor not working? [Solved] on: January 24, 2013, 06:29:08 pm
Hello...

I'm attempting to control a salvaged VFD display from a CD player. I power the filament from the arduino (3.3V). I power the grids and segments from an external 12V power supply.

I can power up a grid and a segment with 12V and it works. That is, I have to two 12V connections active (grid + segment). Now, I would like to turn the connection powering the segment on & off from the arduino using a transistor. Looking at the specs of the BC547B NPN transistor (See below), my understanding is, that it should work.

I insert the transistor in the connection to the segment (12V to the collector, emitter to the display). I thought I could now turn on the segment by connection 3.3V or 5V from the arduino to the base of the transistor, and the segment would light up.  This is not the case however. What could be wrong? I have been experimenting with LEDs and transistors with the 5V from the arduino with success.

Any guidance, hints or suggestions much appreciated.


Some info on the VFD:
Filament draws 111mA (3.3V).
A grid draws 3mA  (12V)
A segment draws 0.2mA (12V)

Transistor info (BC547B):
Vcb max(V): 50
Vce max(V): 45
Veb max(V): 5
Ic max(A): 0.2
hFE (min): 200

Thanks,
Tobias
5  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 29, 2010, 12:13:45 pm
Looking at the PCB through a magnifying glass does, unfortunately, not reveal any bad solders to my untrained eye (The arduino was factory assembled).
6  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 29, 2010, 05:16:34 am
Quote
Have you checked the signal level of reset line while the thing isn't working?

Measuring the RESET->GND on non working arduino:
1. 5v (From what I can tell) when powered on.
2. 0v when reset button is held.

Thanks
7  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 29, 2010, 04:03:25 am
Quote
When it is not working is there 5V on the line?
Yes.

Quote
When it is not working will pressing the reset button bring it back again?

Pressing the reset button has no effect as far as I can tell.
8  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 29, 2010, 01:37:20 am
Quote
You don't seem to believe us

Of course I believe you. I'm just trying to give you as much information as possible.

Arduino stopped working again last evening. Could not get it going. Left it on the table over night.

I observed something new. Maybe it's a clue to someone:
The arduino works the 1st time it's connectede to power. If I cut the power on the working arduino and re-attach power, it no longer works (The program does not run).

So, to me it looks like something prevents the program from running. What could be the cause?

Quote
However being pragmatic and seeing that you can't find out what is wrong then get another board.

I have, but I would REALLY like to know what's going on with the old board.

Just to make it clear: All the comments in this thread are MUCH appreciated in case I come off as being unappreciative!
9  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 28, 2010, 08:27:24 am
I have tried different USB cables and computers all known to be working before.

Powering the arduino on using USB and battery results in different flashing of the on board TX and RX LEDs. I don't know if that's what to expect, but I'll report below anyway.

Attaching a 9V battery to the arduino:
1. PWR LED turns on.
2. TX and RX LEDs blink once.

Attaching arduino and computer using a USB cable:
1. PWR LED turns on.
2. TX and RX LEDs blink 3-4 times (from what I can tell).
10  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 28, 2010, 08:13:16 am
It just stopped working again. Nothing is connected to the Arduino. So, just to be very clear:

1. Power arduino on using USB. Program prev. uploaded to arduino runs as indicated by blinking on board LED.
2. Disconnect USB. Leave of (30+ mins)
3. Reconnect USB. Program no longer runs as indicated by no blinking on board LED.

Can this be anything but a faulty arduino?
11  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 28, 2010, 04:45:11 am
So my observations of a (working -> not working -> working) bare arduino indicates a faulty arduino?
12  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 27, 2010, 01:09:46 pm
I'm not sure it's just the arduino. I have:

1. Removed the shield.
2. Seen the arduino not working.
3. Waited.
4. Arduino works again.

I'm wondering: Can the arduino be in some state that would resolve it self/change after some time?
13  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino randomly works/does not work? on: September 27, 2010, 10:09:50 am
Would that theory also explain why the arduino is not working for some time (turning it on from time to time to check) and then start working again later (30+ min)?
14  Forum 2005-2010 (read only) / Troubleshooting / Arduino randomly works/does not work? on: September 27, 2010, 08:13:36 am
Hello....

I'm working on a project using the data logger shield for my arduino. I'm suddenly seeing some very odd behaviour.

I'm using a duemillenove.

This is what I experienced:
0. Working shield with two sensors. Blinking pin 13 LED on arduino.
1. Added a LED (With resistor) to pin 13 on shield.
2. Re-attach shield. Blinking LED did not come on as expected. Cut power.
3. Detached shield. Blinking LED (on board) still not on.
4. Waited (power off)
5. Arduino working again (No shield). On board pin 13 LED blinking.
6. Re-attached shield. LED blinking as expected. Turn off.
7. Power on. LED not blinking.
8. Remove shield. Still no blinking LED.
9. Can't upload to the arduino from any of three, known to work, computers.
10. Waited (Power off). Arduino working again??
11. Re-attached shield. Everything working.

Any ideas about were to look for the reason for the behaviour? Is my arduino dead?

Thanks
15  Forum 2005-2010 (read only) / Interfacing / Re: Sensing stacked bricks on: November 15, 2010, 09:53:14 am
Quote
How about adding a onewire device, e.g. DS18B20 or DS1307 etc in every brick.

I'm not familiar with one-wire devices. I will investigate. Thank you for the input.
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