An Arduino based DDS-60 controller



Anonymous (not verified)

Sat, 08/04/2012 - 16:49

Why do you show a +12v supply to the Arduino? I assume the DDS60 needs it (I have the AD9850 which is +5v max). The Arduino, if I recall correctly, has a max input of +7v. What am I missing?

The RBBB board has a three terminal regulator so you can supply it with 12 volts. The Arduino chip itself only gets 5 volts.

I don't recall the regulator on the RBBB getting excessively hot but, now that you've mentioned this, I notice that the specs on the RBBB board say 5 to 12 volts. Given that "12 volt" power is usually more like 13.5 or so, I guess it would be a good idea to put a resistor in series with the power line into the RBBB. If a value was chosen to reduce the voltage a bit then it would help dissipate some power and keep the RBBB's regulator cooler.

The specifications here say 4v p-p into 50 ohms.

It's a while ago now but when I looked at it on an oscilloscope I seem to remember that the waveform looked a little distorted at that level.

If you keep it at, say, 2v p-p then if my math is correct that's about 10 mw of power into 50 ohms. If you can get 3v p-p then that's about 22 mw.

Anonymous (not verified)

Thu, 01/24/2013 - 22:09

feed it 5v directly as I have seen elsewhere.

The backlight on my display is an LED so it definitely needs a current limiting resistor. The 560 ohm gave me reasonable brightness at 12v. I'm no expert on LEDs but current is the important measurement, not voltage. They're basically a forward biased diode so the voltage across them is fairly constant. You control the brightness by varying the current.

I think I have seen circuits with the backlight connected directly to 5v as you describe. I can only assume in those cases that the display has a current limiting resistor built in. Maybe yours is like that but you'd want to be sure. You don't want to connect an LED directly to a voltage source.

It doesn't make sense to me to regulate the voltage to the backlight LED. If it is just going through a built in or external resistor then it doesn't need a precise voltage. The little regulator on the Arduino RBBB board is hot enough already so you wouldn't want to put more current through it unnecessarily.


You comments make good sense, and I agree. The light turned on in my head, THANK YOU! I will try a variable resistor from the Arduino's 12V to bias the backlight LED to "ON", like I have done with LEDs in another project I built. Many thanks!!

Your comments will send me back to the books to study diodes again. This is a hobby I learn so much from!


Dave (not verified)

Tue, 02/26/2013 - 17:54



Thanks again for your efforts.

charles (not verified)

Thu, 10/03/2013 - 01:23


Art (not verified)

Mon, 10/28/2013 - 08:52

I agree that this design makes an excellent VFO! I have built several (single band) versions of this and have settled on this as my 'standard' VFO. One caution to anyone who wants to work on / modify Ross' code - the Arduino compiler vs 1.0 works fine but following versions do not produce executable code (for me). I have been too lazy to try to figure out why, so I just keep a copy of vs 1.0 on hand for when I have to re-compile. Many thanks to Ross for the fine work! OBTW I laid out a PCB for the design with an Ebay module but it uses a 'dork' board for the processor - so its probably not useful to many others.







What about working with display type like this?

RS = 12
E = 13
D7 = 7
D6 = 6
D5 = 5
D4 = 4

mine is not working with

LiquidCrystal lcd(A0, A1, A2, A3, A4, A5);


Anonymous (not verified)

Thu, 02/26/2015 - 06:41

In reply to by Gelvis (not verified)

instead of 'LiquidCrystal lcd(A0, A1, A2, A3, A4, A5);', use
LiquidCrystal lcd(14, 15, 16, 17, 18, 19);

Bob N9KR (not verified)

Tue, 11/24/2015 - 12:10

73, Bob N9KR

Rich Carstensen (not verified)

Sat, 12/12/2015 - 16:31


Rich W8VK

WB6LA (not verified)

Fri, 02/10/2017 - 05:58

toroids for so many filters. Cheers,