The D70Box project is documented in Practical Wireless, October 2019. If you require further information, such as the associated circuit diagram or a PCB, then please contact me at [email protected].
The project seems to have been rather popular with over 50 PCBs being shipped and, I assume 50 units being built. I think the reason for this is all down to the project keeping the look and feel of the original D70. It was an iconic look and people seem to be very nostalgic about it.
Fonts! I originally thought that the label font was "microgramma d bold extended" but having listened to Kermode and Mayo's Film Review podcast recently I think it might be "eurostile bold extended"! References to this font include:
A small design fault has been noticed. On the 74LS00 quad NAND gate pins 1,2,3,4,5,6, and 7 are all connected to ground. Pins 3 and 6 should have been left unconnected. This will not impact the overall functionality of the device but may result in slightly more current drain.
The suggested fix, for those who have soldered the 74LS00 directly onto the board and for those using a DIL socket, is to simply snip off pins 3 and 6.
V1.4 of the PCB is now available that will fix the problem without the need to snip off pins.
Some of the Arduino Pro Micro devices seem to be identifying themselves as "LilyPad Arduino USB" devices. If the one you have claims to be one of these then under Tools > Boards select the "LilyPad Arduino USB" device and not "Arduino Leonardo".
Some Arduino Pro Micro devices also seem to be "Leonardo ETH" devices. A symtom of having the wrong Leonardo device selected seems to be odd data being displayed on the attached Bluetooth device.
A problem has been reported building the code with the Arduino 1.5.6-r2 IDE. This manifests with an error saying "SwitchStates does not name a type". If you are facing this issue then please contact me at [email protected] and I'll provide the fix.
A problem has been reported where random 'Z' and random '9' characters were not being generated as expected. This has now been fixed. Version number changed to V1.1.
Do shop around for these devices on ebay. I've noticed that the prices associated with the links below have risen. You should be aiming to pay around £4 - £5 for the Arduino Pro Micro, or less if you buy from China, and £2 - £3 for the Bluetooth module.
The circuit is based around the Arduino Pro Micro. This was purchased via ebay from the URL https://www.ebay.co.uk/itm/1-2-5-10PCS-Pro-Micro-ATmega32U4-16MHz-5V-Replace-Pro-Mini-ATmega328-For-Arduino/283052304952?ssPageName=STRK%3AMEBIDX%3AIT&var=583438190183&_trksid=p2057872.m2749.l2649 but it must be noted that other vendors supply this device too! Other vendors, especially if you are willing to wait, sell these much cheaper!
The HC-05 Bluetooth module was also purchased via ebay from the URL https://www.ebay.co.uk/itm/HM-10-BLE-Bluetooth-4-0-CC2540-CC2541-Serial-Wireless-Module-Arduino-F/123600639430?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 but it must be noted that other vendors supply this device too! The device is advertised as the HM-10 but it should be fine.
Other components include:
Resistors
- R1 150
- R5 2K
- R6 1K
Variable Resistors
- R2 10K Lin
- R3 10K Lin
- R4 22K Lin (Switched)
Semicondictors
- Q1 BFY51 or 2N3019
- U2 74LS00
Miscellaneous
- U3 Switch SPDT centre off
- S1 3.5 mm switch mono socket
- S2 3.5 mm switch mono socket
- SP1 8 Ohm speaker
- Header pins as required
DIL sockets for U2 Header sockets for Arduino and Bluetooth adapter
Start by installing the Arduino IDE. This can be found at:
https://www.arduino.cc/en/Main/Software
For the purpose of this build the Windows version Arduino 1.8.8 was used. All default installation options were accepted.
- Download the associated ZIP file and uncompress it on your drive
- Open the Arduino IDE and then open the D70Box.ino project file in the Source\D70Box folder
- Navigate to Tools > Boards and select "Arduino Leonardo" (See Erratum above)
- Click the "Verify" button (Round circle with a tick mark in it - top left), if successful you will see something like "Sketch uses 14522 bytes (50%) of program storage space. Maximum is 28672 bytes. Global variables use 741 bytes (28%) of dynamic memory, leaving 1819 bytes for local variables. Maximum is 2560 bytes." though the number may not be exact.
- Make sure that the Arduino is plugged into your PC. Navigate to Tools > Port and make sure that the correct port is selected. See USB Issues below.
- Click the "Upload" button (Right pointing arrow - top left) to up load the software.
- The device should now be programmed correctly.
Some users have reported issues connecting the Arduino to the PC USB 3.0 sockets. It seems that the Arduino Pro-Micro is happier connected to a USB 2.0 sockets for programming. More information can be found here: https://learn.sparkfun.com/tutorials/pro-micro--fio-v3-hookup-guide/all
- V1.4 - September 29th, 2019 - Fixed the issue with 7400 outputs pins 3 and 6 being tied low.
- V1.3 - June 4th, 2019 - Fixed legend for T1, should read BFY51 and not BFY71.
- V1.2 - May 24th, 2019 - Added BlueTooth support.
- V1.1 - ?
- V1.0 - April 5th, 2019 - Initial board design.
I have managed to re-create a realistic looking D70 knob. The knob is designed to provide a friction fit to a knurled 6mm diameter shaft - split or otherwise. The 3D design has been created using OpenSCAD - see https://www.openscad.org/
The OpenSCAD source file and associated STL file can be found in the 3DPrints folder.
The Delay and Speed setting may seem wrong relative to the knob position. The best way to check this is to use the BlueTooth interface and look for the Delay and Speed setting. Adjust the two control until the values displayed match values on the legend. Then adjust the knobs so that the indicator is as close as possible to the legend value. The attained proximity will depend on the potentiometer shaft type, smooth or knurled / serrated etc.
The BFY51 transistor can be substituted with a 2N3019. See https://ham.stackexchange.com/questions/8990/can-anyone-please-suggest-a-substitute-for-the-bfy51-transistor/9031
The Bluetooth card may prompt for a PIN, this is likely to be either 1234, or 0000.
David, G4DMP, has sent in a picture of his completed build.
David, G4EDR, has also sent in a picture of his completed build.
Stephen, GI7ISX, has also sent in a couple of pictures of his completed build.
