ZeroFossilFuel CCPWM v2.x PC Board

Custom PC Board for Zero Fossil Fuel's Constant Current PWM v2.x

Revision 3 board allows AFS recommended upgrades to be included in your PWM.

A fully assembled PC board with AFS upgrades is available. Click here.

This custom PC board is for those who wish to "build your own" ZeroFossilFuel's version 2 constant current PWM, including version 2.1 and heavy duty design.   Buy this printed circuit board and save time building Zero's CCPWM.  Provisions are included to optionally add Alt Fuel Systems modifications for duty cycle stabilization and improved MOSFET drive capability.  The modifications reduce MOSFET heating and improve longevity with the addition of a few components.

A printed circuit board is much easier to assemble than a prototype vector board. There is no need to create the circuit during assembly which can be difficult and time consuming. With a custom PC board you simply insert the components and solder. We have built Zero's PWM using both the vector board and the custom PCB. The vector board assembly took over 6 hours. We assembled the custom PCB in under 20 minutes.

The PCB is a durable high quality product.  Tin plating protects the copper traces from oxidation and aids soldering.  The green soldermask layer resists solder to reduce the likelihood of solder bridging (short circuits caused by solder between two solder joints), and the white silkscreen  printing clearly labels component positions. 

The PCB was designed to fit in the G106 enclosure, and is notched to avoid the extra effort required for tab removal. The board can be used with other enclosures, or in "open air" for bench top testing.  Component designations labeled on the board match the designations in Zero's schematic.  Bourns 3296Y series potentiometers are required for this board. Solder pads for wire hookup will accept wire gauges up to 18AWG.  We recommend mounting the hook up wire on the back side of the board to keep the pot adjustment screws clear.  Vector push in terminals are not required. The board is RoHS Compliant/Lead Free.

NOTE:  This board can be used to drive a 110/220VDC PWM when a properly selected MOSFET and shunt resistor is installed. (Recommended for experienced installers only.)

Revision 3 updates

• Addition of a second gate resistor (R9b) and a second gate wire solder pad for dual MOSFET systems.
• Eliminated the ground wire solder pad.  The board is now grounded through the mounting screws.
• Addition of solder pads for a 12VDC cooling fan power connections.
• Improved ground plane distribution.  Increased trace width.
  
• Added provisions for mounting an optional FET driver on the back of the board to help MOSFETs run cooler, and to allow connecting several MOSFETs for high current systems.
  
• Wire connection solder pads reduced to 18 gauge maximum wire size.
• R14 silkscreen label changed to R14/L1
• Added C9 to stabilize output frequency when current limiting is active.
• PC board layout allows several configurations to be assembled including ZeroFossilFuel's original design, his new heavy duty design, and several upgraded designs developed by Alt Fuel Systems.
  

For additional images, assembly options and a schematic, click on the product image above.

Circuit design credits go to ZeroFossilFuel.  He created the original circuit and released it under a general public license so we can all benefit from its use.  Additional circuit information is available at ZeroFossilFuel's website alt-nrg.org.  Alt Fuel Systems produces this printed circuit board.  It can be used to assemble the original design of the circuit or modified versions created by Alt Fuel Systems.  See the schematic for additional options.

Why add a FET driver?

Most of the heat generated by the MOSFETs occurs during the time the MOSFET is changing between its on and off states.  When turned on, resistance is very low and current is high.  Using the power equation (Power equals current squared times resistance), the low resistance yields a low power dissipation (less heat).  When the MOSFET is off, resistance is high and current flow is zero.  Here the power equation shows low power dissipation because of zero current flow.  When the MOSFET is changing between the on and off states, there is current flow through resistance that produces heat.  The gate of the MOSFET (the on/off control) is essentially a capacitor that must be charged and discharged to turn the MOSFET on and off.  In Zero's design the gate capacitance is charged/discharged by an op-amp which has a current limitation that causes the gate to charge slowly.  Adding a FET driver between the op-amp and the MOSFET gate reduces the time it takes to transition between between the on and off states because the FET driver can supply much higher current to the gate. The higher current charges the gate much faster, the MOSFET switches much faster, and the amount of time the MOSFET can produce heat is reduced.  Simply put, COOLER MOSFETs.  Click on the PC board image above to view the difference on an oscilloscope.  The FET driver specified in the parts list can supply a 6 amp pulse to the gate.  This is much higher than the 40 milliamp limit of the op-amp.  The FET driver should be considered a required upgrade in multiple MOSFET systems.

Board dimensions: 2.300 in. x 1.325 in.
Mounting holes accept 1/8 in. screws.
(PC board dimensions are the same as the revision 2 boards.)

PC board only, does NOT include any additional components or documentation.

Recomended Parts List
The first part of this list is for components on the PC board. The second part lists additional components required to build the complete PWM V2 as shown on ZeroFossilFuel's website. This list of components is for all assembly variations.
You may substitute equivalent components in most cases without affecting circuit operation.  Be sure to check component dimensions when substituting to be sure they will fit on the PC board.  If you're not sure how this is done, we recommend using the part numbers listed. Updated: June 28, 2010
PART 1 PC board components
Designation	Part	Qty	Description	Supplier	Part No.
	PC Board	1	Zero's PWM V2.X PCB	Alt Fuel Systems	AFS-PCBPWMV2R3 $10.99 ea
U1	LM324N	1	Quad Op-Amp	Alt Fuel Systems	STM-LM324N $0.44 ea
				Mouser	512-LM324N $0.54 ea
U2	7810	1	Positive 10V regulator	Mouser	512-LM7810ACT $0.38 ea
U3	TC4420	1	FET Driver	Mouser	579-TC4420EOA $1.71
R1, R7	1.8K	2	1/4 Watt 5% Resistor	Mouser	660-CFS1/4CT52R182J $0.05 ea
R2	22K	1	1/4 Watt 5% Resistor	Mouser	660-CFS1/4CT52R223J $0.05 ea
R3, R4, R5	10K	3	1/4 Watt 5% Resistor	Mouser	660-CFP1/4CT52R103J $0.05 ea
R6	3.9K	1	1/4 Watt 5% Resistor	Mouser	660-CFS1/4CT52R392J $0.05 ea
R8	100K	1	1/4 Watt 5% Resistor	Mouser	660-CFS1/4CT52R104J $0.05 ea
R9, R9b	100	2	1/4 Watt 5% Resistor	Mouser	660-CFS1/4CT52R101J $0.05 ea
R10, R13	1K	2	1/4 Watt 5% Resistor	Mouser	660-CFS1/4C102J $0.05 ea
R11	1M	1	1/4 Watt 5% Resistor	Mouser	660-CFS1/4CT52R105J $0.05 ea
R14/L1	10	1	1/2 Watt 5% Resistor	Mouser	660-MF1/2LCT52R100J $0.13 ea
	100 uH		Inductor (recommended)	Mouser	542-77F101-RC $0.18 ea
VR1	10K	1	Multi-turn trimmer potentiometer	Mouser	652-3296Y -1-103LF $2.20 ea
VR2	20K	1	Multi-turn trimmer potentiometer	Mouser	652-3296Y-1-203LF $2.20 ea
VR3	1K	1	Multi-turn trimmer potentiometer	Mouser	652-3296Y-1 -102LF $2.20 ea
C1	0.022uF	1	Polyester Film Capacitor	Mouser	598-DSF050J223 $0.20 ea
C2, C4, C9	47uF	3	Electrolytic Capacitor	Mouser	140-L35V47-RC $0.32 ea
C3	0.047uF	1	Ceramic Disc Capacitor	Mouser	140-100Z5-473Z-TB -RC $0.16 ea
C6 (pcb)	1nF	1	Polypropylene Capacitor	Mouser	505-FKP21000/100/5 $0.34 ea
C8	4.7uF	1	Ceramic Capacitor SMD	Mouser	81-GRM32RR61E475KA12 $0.80 ea
PART 2 Additional PWM components.
Designation	Part	Qty	Description	Supplier	Part No.
Q1	IRFP064N	see note	Power MOSFET	DigiKey	IRFP064NPBF-N D $2.18 ea
D1	MUR420G or equiv	1	Fast recovery diode	Mouser	863-MUR42 0G $0.43 ea
R12	14AWG 105˚C stranded copper hookup wire (6 inch 0.0015 ohm)	6in	Wire Pack: Several 1 ft lengths in multiple colors	Alt Fuel Systems	AFS_PWM2WIRE $3.99/kit
			100 ft roll	DigiKey	C2105W-100-ND $43.60 ea
C5	4.7uF / 100V	1	Polyester film	Mouser	5989-100V4.7-F $2.38 ea
C7	12,000uF / 25V	1	Electrolytic cap	Mouser	661-EKMH250VNN1 23MP $2.73 ea
	18AWG 105°C stranded copper hookup wire	3ft	Wire Pack: Several 1 ft lengths in multiple colors	Alt Fuel Systems	AFS_PWM2WIRE $3.99/kit
			100 ft roll	DigiKey	C2103W-100-ND $24.53 ea
	Binding post	1	Red binding post for positive supply (optionally used in place of the #10 lug)	Alt Fuel Systems	EMR-11-0102-001 $2.14 ea
				Mouser	530-111-0102-1 $2.01 ea
	TO-247 thermal pad	see note	Aluminum oxide	Mouser	532-4180, $0.70 ea
			Mica	MCM Electronics	21-1170 $4.29/25
	Heat sink compound	1g	Heat sink compound	Mouser	526-NTE303 $2.77 ea
	Heatsink	1	CPU cooler w/ fan	NewEgg	N82E16835150018 $8.98 ea
			CPU cooler w/ fan	Directron	FAN-ALU-7 $3.99 ea
			Small CPU cooler no fan	Mouser	567-628-65AB $3.20 ea
	Ring terminals	3	#10 stud, 12AWG	Mouser	538-19069-0209 $0.17 ea
	Aluminum enclosure	1	Vellman G106 or equivalent	Mouser	563-AN-1302 $9.40 ea
				Digikey	377-1101-ND $9.40 ea
	Fibre shoulder washer	2	Keystone #3239 or equivalent	Mouser	534-3239 $0.14 ea
	Fibre flat washer	2	Keystone #3130 or equivalent	Mouser	534-3130 $0.08 ea
	#6-32 x 3/8" screws	1	To mount the stiffening cap ring terminal.
	#6-32 x 3/4" screws	2	To mount the MOSFETs.
	#6 lock washers	3
	#6 flat washers	3
	#10-24 x 1" screws	3
	#10-24 hex nuts	6
	#10-24 wingnuts	3	may subistute hex nuts
	#8 flat washers	5	for a snug fit on #10 screw
	#10 split lockwashers	6
Misc: Tools, solder, #6-32 threading tap, drill bits.
NOTE:  One MOSFET and one thermal pad is required for ZeroFossilFuel PWM versions 2.0 and 2.1.  Two MOSFETs and two thermal pads are required for version 2.1H (heavy duty)