DC Servo 2v68: nAn0 Und3rP4nTs
The nAn0 Und3rP4nTs DC Servo is a fully isolated medium power motor driver shield for the Arduino Nano supporting motors up to 85v. Isolated meaning you can safely use the USB on the Nano without fear. Additionally no more high power ground loops! The Shield entertains a number of useful features including:
- High speed optical isolators for PWM.
- Hall sensor isolated analog current feedback.
- Five tuning potentiometers for gains and limits.
- Control header featuring step, serial, i2c and analog.
- Switched cooling fan with RPM feedback.
- Two status LEDs and mode button.
- Single supply motor and gate power.
Onward to the assembly:
INSTRUCTIONS
When assembling a circuit board, start with the shortest components first.
This way, when the board is turned over to solder, the parts rest on the table and don’t fall out.
1. RESISTORS
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Bend each resistor before inserting them. The resistors are marked with 3 colored bands to indicate value. The fourth colored band is typically gold or silver and this indicates tolerance. The value and color code for each resistor is in the chart. |
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On the board – each resistor is labeled ‘R’ followed by a number. The numbers increment in a pattern, starting at the top left of the circuit board. R1 is much larger being that it is rated for 2 Watts, it’s good to leave a space (2~5mm) for cooling between the PCB and the resistor for this part. |
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| Solder each resistor in place and then trim off the extra bits. | |||||||||||||||||||||||||
2. DIODES
| There are 3 different diode types that are 3 different sizes. The footprints on the PCB are similar, a rectangular part with a stripe to indicate polarity. |  |
| The smallest diode part is BAW76, it has an orange glass body. Place it according to the stripe. There are 6 of them, the part numbers are D5, D6, D7, D8, D12 and D13. |  |
| The medium size diode is a 1N4937 which will be printed on the diode body. There are 4 of them, the part numbers are D9, D10, D11 and D14. |  |
| The largest diode is a fast TVS (transient voltage suppressor), part number P6KE170A. There are 4 of them, they are part numbers D1, D2, D3 and D4. |  |
| Carefully flip the board over. Solder each capacitor in place, and then trim off the extra bits. |
3. CERAMIC CAPACITORS
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There are four different kinds of ceramic capacitors on the PCB and some of them look similar. Most of the footprints are the same, some are more rectangular shaped. |
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The first ceramic capacitors are labeled ‘104’ which means 10 + 4 zeros pF (0.1uF) and are rated for 25 or 50v. They should be yellow, and small but sometimes they are blue. It is 5mm between pins. The part numbers are C8, C9, C10, C11, C15, C16, C18, C20 and C21. |
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The second ceramic capacitors are also 104 but are rated for 250v. They are much bigger and are red-brown color. The part numbers are C3, C4 and C5. |
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The third ceramic capacitors are label 224k which is hard to read. They are bigger as they are rated for 250v. The K on the label indicates the tolerance of 10%. The part numbers are C6 and C7. |
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The fourth ceramic capacitor is 105 (1uF) and rated for 25v. See the label on the part, it reads 105K. The part number is C14. |
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| Carefully flip the board over. Solder each capacitor in place, and then trim off the extra bits. |
4. ELECTROLYTIC CAPACITORS
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There are a bunch of electrolytic capacitors in the circuit. The voltage rating is very important! Note – The white stripe indicates negative. |
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On the footprint, the white half circle marks the negative terminal. The shorter leg of the capacitor goes in the negative terminal. |
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| Place, flip & solder, then trim the leads. | |||||||||||||||||||||
5. IC SOCKETS
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There are four chips sockets, two are for the optocouplers and two are for the gate drivers. They are all 2×4 size. The part numbers on the PCB are IC1, IC2, OK1 and OK2. |
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| As they are just holders it doesn’t really matter which way they fit but you should line up the notch regardless. Place, flip, solder. |  |
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After soldering, the chips can be inserted. |
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6. TRANSISTOR
| The transistor is a switch. This part is a BC548, a small signal NPN transistor. There is one of them in the circuit, it is Q5. Be careful not to confuse it with the small 78L05 voltage regulator which is part VR2. Read the label. |
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| The shape of the body determines how it fits. Match the round and flat edges to the footprint on the circuit board. Place, flip, solder, trim. |  |
7. SMALL VOLTAGE REGULATOR
| This regulator has a TO92 footprint just like the transistor in step 6 above. Read the label. It is VR2 and is a LM78L05, the L in the middle of the name indicates its the smaller part rated for 100mA. |
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| The shape of the body determines how it fits. Match the round and flat edges to the footprint on the circuit board. | |
8. LARGE VOLTAGE REGULATORS
| These regulators have a footprint just like the MOSFETs in step 9. Read the label, make sure you have the right part. |  |
| The first part is LM7805 and is part number VR3. The second part is TL783CKC and is part number VR1. The metal tab of the part matches the rectangle on the footprint. |  |
9. MOSFETS
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These parts are the main switches for the motor, they are IRF540 N-Channel MOSFETS, a large transistor. Be careful, the footprint looks the same as the voltage regulators in step 8. Read the label, make sure you have the right part. NOTE: THEY ARE SENSITIVE TO STATIC ELECTRICITY, BE CAREFUL UNTIL THEY ARE SOLDERED IN THE CIRCUIT. |
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| There are four of them, they are part numbers Q1, Q2, Q3 and Q4. The metal tab of the part matches the rectangle on the footprint. | |
10. SCREW TERMINALS
| There are 3 screw terminals, two are green and one is blue, the footprints look like this. The rectangle denotes the negative terminal where applicable. |  |
| The green screw terminals are larger and have a higher power rating. They are for the motor and the motor power, both on the same side of the board. |  |
| The blue screw terminal is smaller and is for the Arduino power. |  |
11. CURRENT SENSE
| This is the isolated hall current sensor PCB. The SMD parts are already mounted and soldered. |  |
| Add the male pin header to the current sense PCB. |  |
| And the female pin header to the servo PCB, it requires cut to size. |  |
| The footprint is on the left side of the PCB and looks like this. The cross hatch area indicates the isolation boarder between the power side and the control side. |
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12. ARDUINO NANO HEADER
| There are two rows on single header (1×15) for the Arduino. | |
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They fit into the footprint on the board like this.You can use your Arduino to stabilize and align them for soldering. The rectangles around some pins indicate the ground connections. |
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13. POTENTIOMETERS
| There are 5 potentiometers in the circuit. They are used to set gains and limits. They are G0, G1, G2, G3 and G4. |  |
| Like most potentiometers, it has three legs and this makes it easy to fit as the footprint illustrates. |  |
14. RED & GREEN LEDs
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The two LEDs are 5mm size. L1 is the Error LED and is red. L2 is the OK LED ans is green. LEDs are polarized, the long leg is positive. Inside the LED, the anvil shape is typically negative. |
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| The footprints looks like this. Be careful of the orientation, match up the flat side of the LED with the flat side of the PCB footprint. Also, the long lead is negative, it’s hole is marked with a square solder pad on the PCB. Place, flip, solder & trim. |  |
15. BUTTON
| The button is a simple 4 legged animal, it snaps in place any which way it fits. There is only one, it is 6mm size. |  |
| It’s footprint looks like this. Make sure the pins are not bent going in. Place, flip, solder & trim. |  |
16. FAN PIN HEADER
| Some single row pin header is included for both the current sense board and the fan header, it looks like this and will require breaking to the correct size. | |
| It’s footprint looks like this. Only the three pins on the right are used, the square pin and the next two, those closest to the edge of the PCB. |  |
17. CONTROL PIN HEADER
| This bit is a 2×6 double row right angle male pin header for the control and encoder interface. Optionally straight pin header can be substituted depending on requirements. |  |
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| It’s footprint looks like this. Refer to the table below for the pin name and function. |  |
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18. STANDOFFS
| The standoffs keep the board up and mount the fan. |  |
| The brass standoffs are for the top. |  |
| The plastic standoffs are for the bottom. |  |
19. FAN
| The fan is attached to the standoffs and plugs into the fan header. The plug should be connected to the three pins closest to the edge of the PCB. The black wire is nearest the PCB edge. Some M3 screws are included to attach the fan to the brass standoffs. |  |
LIBRARIES & SKETCHES
| Not yet published. | |
when are planning to publish the schematic and PCB + code (hopefully C language) so we can benefit from the project .
and does is this design better than the old one found here :
http://krazatchu.ca/wp/2009/05/31/dc-servo-drive/
i had a couple questions regarding that design can u answer them ?
Hi, looking good, is this one finished or in progress?
Will it still be open source?
Thanks, Don
please contact me by email
many thanks & will share my project
328p servo drive
Thanks Paul
Is this project dead? Or will be there any continuous developmnent in the near future?
hey need servo on atmega328 ..means with arduino uno
great work ! i cant find your code and eagle file
any instruction on tunning and etc else.. please !
wow awesome i noticed that u used poentiometer to tunning really appriciate you great works now i relly need scketches and eagle files thanks in advance my mail is cktandel@yahoo.in
I’m interested in the source and eagle files for this project, please contact me, thank you.
Are you working on this project? Can You please send me scketches for nanno? My mail: joker691@gmail.com
Thank You