The board has four sections: power distribution, timers, the gate driver, and the MOSFET power transistors.
This board is designed to plug into a standard female hard drive power connector (Molex Connector), though it can also be powered from a fairly wide range of sources.
The timers are six common 556 (dual 555) chips. These have the advantages of being cheap, easy to find (often salvageable from old boards), and familiar to many people. They are simple, stable, rugged devices. Two timers (half of two separate ICs) are used for each modulator. Jumper JP2 is provided to run the timers off either VCC or VDD. Low-leakage capacitors are best, especially for generating low frequencies and long pulse width; one engineer [VROON] recommends tantalum caps. A Philips Applciation Note has the following gem.
Under no circumstances should ceramic disc capacitors be used in the timing network! Ceramic disc capacitors are not sufficiently stable in capacitance to operate properly in an RC mode. Several acceptable capacitor types are: silver mica, mylar, polycarbonate, polystyrene, tantalum, or similar types.
These timer chips are notoriously sensitive to noise, and are prone to generate it themselves, so there are plenty of pads provided to mount bypass capacitors. In addition to extra through-hole pads for leaded capacitors at the power and ground pins of each IC, you can surface-mount up to nine more on the 0805 pads provided on the solder-side of this board. One or more 0.1μF ceramic capacitors for each timer chip are almost universally recommended by circuit designers.
It takes a little math to configure the timing resistors and capacitors needed for either pulse width (constant frequency) or pulse frequency (constant pulse width) modulators. The timer frequency is determined by the values of capacitor C1-xxx, resistor R1-xxx, and potentiometer TP1-xxx. Note the minimum potentiometer values (TPxmin) to use in these formulas include the value of the optional minimum-value resistor installed in series with each potentiometer. The following formulas show how to do these calculations using the suggested 0.1μF capacitors for both C1 and C2, a 3.3kΩ resistor for R1, and 10kΩ-1MΩ pots TP1 and TP2.
f = 1/(0.693 × C1 × (TP1 + (2×R1) ))
f = 1/(0.6933 × 0.1×10-6 × (TP1 + (2×3300) ))
f = 1/(69.33×10-9 × (TP1 + 6600 ))
fmin = 1/(69.33×10-9 × (TP1max + 6600)) = 1/(69.33×10-9 × (1000000 + 6600))
→fmin = 14.33 Hz
fmax = 1/(69.33×10-9 × (TP1min + 6600)) = 1/(69.33×10-9 × (10000 + 6600))
→fmax = 868.9 Hz
The pulse width is determined by the values of capacitor C2-xxx and potentiometer TP2-xxx.
t = 1.1 × C2 × TP2 = 1.1 × 0.1×10-6 × TP2 = 110×10-9 × TP2
tmin = 110×10-9 × TP2min = 110×10-9 × 10000
→tmin = 1.1×10-3 sec = 1.1 msec
tmax = 110×10-9 × TP2max = 110×10-9 × 1000000
→tmax = 0.11 sec = 110 msec
Adjusting the pulse width to be longer than one frequency cycle will cause strange things to happen. Try to keep t < 1/f.
There are dozens of web pages explaining these formulas in more detail, one of the reasons for using the ubiquitous 555 timers in this design. There are even zillions of online calculators available. Just put ‘555 calculator’ into your favorite search engine, or use this handy Google search link.
The left side of the board is laid out so you can use almost any small potentiometer or trimmer with 0.1″ lead pitch, and there are extra pads to provide an additional minimum resistance to each pot if needed. Use either standard leaded resistors mounted vertically or (0603 or similar) surface-mounted resistors from the center-right square pad to another square pad in the group. Which pad you use will determine the direction of potentiometer response; changing from one adjacent pad to the other will reverse the response of the pot.
If your pot already provides the minimum resistance you need, you must place a wire jumper (zero-Ohm resistor) from the center square pad to one other square pad in the group.
Which other square pad you use will determine the direction of the response of the associated pot. In addition, you can use these pads to attach leads from panel-mounted pots or some other source of resistance such as thermisters or photoresistors. By choosing suitable resistors, capacitors, and MOSFETs, most modern timer ICs should be able to generate frequencies and pulse widths to utilize the full DC-100kHz range of the gate driver.
The HIP4086 is a modern chip designed for use as a three-phase motor controller, but its configuration options allow it to be used in many other applications.
The high-side inputs are inverted.
The gate driver provides the high current pulse necessary to drive almost any common NPN MOSFET.
Optional Surface Mount Components
In addition to additional bypass capacitors, extra pads are provided to use surface-mount packages on the bottom of the board in place of the resistors and capacitors used for the timers.
This PCB has been designed to be as versatile as possible.
- Drill holes, solder pads, and clearances have been made as large and wide as possible.
- The PCB is laid out for physically large leaded resistor and capacitor packages to allow the use of as wide a range of components as possible.
- Where possible, both through-hole and surface-mount solder pads are available.
- Where both polarized and non-polarized capacitors may be used, the through-hole solder pads for the positive terminal are square and the negative terminal pads are round.
- Most of the pads for the (optional) surface-mount components are on the solder-side of the board so you can still get to them with through-hole components installed.
Be careful to note how your Molex hard drive power header assembly attaches to this board. It was designed for a horizontal socket with the connector bevel on the same side as the pins so the bevel faces the top side of the board after mounting (as in this drawing), but another type of header may be used if it is oriented correctly. When looking down at the top of your board with a standard hard drive power cable plugged in, the red +5V wire should be to the left (VCC), while the yellow +12V wire is nearer the MOSFETs to the right (VDD).
If your Molex connector is backward, turn it around if space permits, or mount it to the other side of the board. If you use a vertical header assembly or some other shape, you may need to mount the through-hole power decoupling capacitors on the opposite side of the connector first.
Mounting this header assembly to the underside has the unfortunate side-effect of covering up the Hackaday logo, but the gate driver needs VDD +7 to +15V from the wire nearest the MOSFETs. The gate driver has under-voltage protection so neither it nor your MOSFETs are likely to be damaged if you accidentally attempt to drive them off of the +5V from a standard hard drive power connector, but they won't work, either.
Although the placement is a bit tight, through-hole assembly of the timer and gate driver portions of this board in its standard configuration should be straightforward.
The twelve potentiometer mounting areas allow for the use of many different tiny potentiometers with 0.1″ lead pitch.
- When placing your pots, make sure the wiper pin (usually in the center) goes into a round hole, and at least one of the other two pins goes into an adjacent square hole.
- In all twelve pot mounting areas, be certain to install a resistor, plain wire, or solder bridge from the center-right square pad to one of its adjacent square pads.
Mounting the MOSFETs and optional screw clamps is a bit more involved. Most important is the orientation of the MOSFETs. The MOSFET gate pins are always closest to the bottom of the board. If the pins are straight and the transistors are mounted to the top side of the board, they will face to the right with their metal surfaces and heat sinks facing left. If the pins are bent 90° and the transistors are off the right edge of the board, they will appear to be upside-down in relation to the board with their heat sinks and polished-metal surfaces facing upward. You may mount them in any combination of top/bottom, straight/bent pins as long as the gate pin is always the closest pin to the bottom of the board, and the source is closest to the top. Mounting the high- and low-side MOSFETs differently may also allow you to attach heat sinks to them more effectively, and is recommended. The 3D rendering shows one example of this kind of placement from the underside of the board. [The MOSFET drawing is from MOSFET Testing [TORRENS].]
Also, if you want to try to cram screw clamps or other connectors onto this board, you will probably need to place them on alternating sides as well just to make them fit. To use the optional decoupling capacitor surface-mount pads, place the low-side connector assemblies on the bottom of the board, and the high-side connectors on the top.
Surface-mount Assembly (Optional)
All of the surface-mount components are optional. Most of the surface-mount device (SMD) pads are on the back, solder-side of this board, and many of the through-hole pads are square to allow substitution with surface-mount components. Series 0805 pads are provided for mounting capacitors, and the smaller 0603 pads are for resistors. Note most of the through-hole solder pads will need to act as vias when their intended components are not present.
If you are replacing through-hole components with surface-mount components, solder short wires to replace the missing leads or at least use a continuity tester to be certain the drill holes for the leaded component are properly plated through.
- Power Plane Decoupling Capacitors CXXX-CXXX
- Use larger-value tantalum caps. [LEROY]
- Timer Capacitors C1-xxx through C2-xxx
- Timer Resistors R1-xxx
- Timer Minimum Impedance Resistors
- Although separate surface-mount pads are not provided, you should be able to attach common resistor packages across two adjacent square pads in the pot mounting areas.
- MOSFET Bypass Capacitors
- These are mounted to alternating sides of the board, on the opposite side of each screw clamp.
- Power Assembly Bypass Capacitors
- It is a good idea to use multilayer ceramics on the pads provided in addition to the larger electrolytic capacitors.
Use of this Device
The timers and modulated power outputs are arranged, from top to bottom, as follows.
- Low-side Driver BLO
- High-side Driver BHI
- Low-side Driver ALO
- High-side Driver AHI
- Low-side Driver CLO
- High-side Driver CHI
Adjust the modulation frequency of each channel using TP1-xxx, the potentiometer on the left, closest to the edge of the board. Adjust the pulse width of each channel using TP2-xxx, the potentiometer on the right.
Though they may all be driven ground-referenced, the MOSFETs are arranged in pairs and can be configured as one to three half-bridges. To do this you will need to short three pins together in an 'L', so one pulsed signal from either the HI or LO timer in a pair drives both the high- and low-side MOSFETS together. Since the high-side gate driver input of each A, B, and C pair is inverted, the associated MOSFETs will form a half-bridge, with neither transistor in the pair being on at the same time.
If you are using this device configured as bridges, remove the jumper shunt and install a 2kΩ to 100kΩ resistor from the RDEL pin of header HD1 to the VDD pin next to it.
An external logical inverter is needed to create a full bridge from two half bridges.
There are six blocks of jumpers. Four sets determine how power is distributed to the circuit and the other two configure the gate driver. In addition, you may replace the minimum-impedance resistors or pots with headers to allow off-board mounting of the potentiometers.
Power Distribution Jumpers
- JP1 Common Ground
- With this jumper in place, VSS will become one with GND, the timer ground.
- JP2 Timer Power Selection
- The three pins of this jumper acts as a single-pole dual-throw (SPDT) switch by placing the jumper across the center pin and either the pin to the right or the pin to the left. Use it to power the timers from either +5VCC (left position) or +12VDD (right position).
- Note by removing this jumper, you could install a TO220-packaged voltage regulator [DIMENG] by bending its pins and connecting it properly.
- JP3 VHS Rail Voltage Selection
- The three pins of this jumper acts as a single-pole dual-throw (SPDT) switch by placing the jumper across the center pin and either the pin to the right or the pin to the left. Use it to select the high-side MOSFET rail voltage from between +5VCC (left position), or +12VDD (right position). Removing this jumper allows the rail to be powered by an external power source from zero to +80V (relative to VSS) when JP4, JP5, or JP6 are in place. This rail should be able to handle a total of about 1½ to 2A on its own.
- Note you can replace this jumper with a TO220-packaged voltage regulator [DIMENG] by bending its pins and connecting it properly.
- JP4A VBHS Grounded to VSS
- JP4B VBHD on Rail VHS
- JP5A VAHS Grounded to VSS
- JP5B VAHD on Rail VHS
- JP6A VCHS Grounded to VSS
- JP6B VCHD on Rail VHS
- Each set of four pins each act as a dual-pole dual-throw (DPDT) switch by placing a single jumper across either the pair to the left or the pair to the right. Never place jumpers on both the right and left pairs in a single set. Never place a jumper in the middle position and be very careful not to short the middle two pins accidentally when power is applied anywhere to the board. Choosing the left, MOSFET source to VSS , position allows you to configure each high-side driver as an additional low-side (ground-referenced) driver. Installing a jumper across the right pair of pins attaches the corresponding high-side MOSFET drain pin to the VHS rail described above. You may attach any number of the high-side MOSFETs to this rail.
- With no jumper installed on either side, the corresponding MOSFET may be powered from an external voltage from zero to +80V (relative to VSS).
- Never place jumpers on both the left and right pair of pins in a single set.
Never place a jumper in the middle position.
HD1 Gate Driver Configuration Jumpers
These jumpers allow you to configure the gate driver. The default configuration of this board is as six independent low-side drivers.
Note the order of these jumpers reflects the pin-out of the HIP 4086 gate driver.
- JP7 BHI High-Side Logic Level Input B—Inverted
- JP8 BLI Low-Side Logic Level Input B
- JP9 ALI Low-Side Logic Level Input A
- JP10 AHI High-Side Logic Level Input A—Inverted
- These can also be used as logic-level inputs for external control.
- VSS (JP11)
- These pins provide access to VSS for convenience.
- JP12 RDEL Dead Time Setting
- To allow all six channels to run independently in the board's default configuration, disable the shoot-through avoidance feature by installing a jumper vertically between the right-side pin of this jumper and the VSS pin directly above it.
- If you configure any pair of drivers as a half-bridge, you should attach a resistor horizontally across these pins to prevent shoot-through (short circuiting). The dead time varies linearly with the resistance: 0.1μS at 10kΩ to 4.5μS at 100kΩ. If you are using all six MOSFETs as low-side VSS-referenced drivers, disable the shoot-through avoidance feature by installing a jumper vertically from the right pin of this jumper to the VSS pin directly above it.
- Installing a female header in this location would allow you to easily alter the dead time by plugging the resistor leads into it. Or, you could surface-mount a resistor across these square solder pads on the underside of the board. (The left-hand pin is VDD.) It should be OK to leave this fairly large-valued resistor across this jumper while shorting the right pin to the VSS pin above it to disable shoot-through avoidance.
- JP13 UVLO Under-voltage Setting
- Do not install a jumper across these pins. By default, the under-voltage disable is approximately 6.6V.
- Do not install a jumper at this location. To change the under-voltage disable setting, attach a resistor across these pins. See the HIP 4086 datasheet [HIP4086].
- JP14 RFSH Refresh Pulse Setting
- Do not install a jumper across these pins. By default, the refresh pulse is approximately 1.5 μs.
- Do not install a jumper at this location. To change the refresh pulse setting, attach a capacitor across these pins. See the HIP 4086 datasheet [HIP4086].
- JP15 DIS Disable Input
- By default, this jumper is in place, tying this pin to VSS and enabling output.
- Apply a logic-level high to the right-side pin to disable output.
- JP16 CLI Low-Side Logic Level Input C—Inverted
- JP17 CHI High-Side Logic Level Input C
- See above.
Wiring the Loads
Be very careful how you wire these FETs to the devices you are powering with them. When you look at the screw clamps straight on, facing the right side of the board (where the Hackaday logo is), the MOSFETs' source pins are connected to the right-side of each terminal block. This pin is always connected to the more negative side of your load, usually VSS, lour loads' ground. Since this terminal is (or can be) connected to your loads' ground on the board, for many applications you do not even need to put a wire into the right-side screw clamp.
To use a MOSFET as a low-side driver, insert the load's ground wire into the left hole of the connector and screw it down snugly. (This wire is usually black or green, but not the bare metal chassis ground.) Then, attach the power wire(s) to the load's power supply. The MOSFET acts like a switch, interrupting the attached load's path to ground.
If you plug this board into a standard hard drive power supply, VCC should be +5V and VDD should be +12V.
- Timer Voltage
- This will usually be +5V (jumper JP2 in the left position) when hooked up to a regular hard drive power connector, though the timers may be run off VDD by moving jumper JP2 to the right. This makes it possible to run the board off of a single +7V to +15V power source.
- Timer ground.
- Gate Driver Voltage
- This will usually be +12V when hooked up to a regular hard drive power connector, but can be any voltage between +7V and +15V relative to VSS.
- Gate driver and MOSFET ground.
- The three low-side MOSFETs switch this voltage potential present on their source pins.
- User 1½-2A Power Rail Voltage
- Use jumper JP3 to select high-side rail potentials from among VCC (left), VDD (right), or VSS (up). Place this jumper pointing upward to VSS to configure all six MOSFETs as low-side switches. Remove this jumper entirely to run connected high-side MOSFETs at a common voltage applied to their drain pins.
- VBHS, VAHS, VCHS
- Each high side MOSFET may be detached from the common rail and driven independently by removing its associated jumper.
- NE556: 4.5-16V, ICM7556: 2-18 V
- Limited by '556s chosen.
- Gate Driver
- May be limited by minimum gate threshold voltage of the MOSFETs
- This datasheet for the IRF510 specifies a VGS of 4-20V. At 7V VGS (the minimum needed for the gate driver IC) 4-5A of drain current (ID) can be maintained through this MOSFET, but it loses linearity of response and becomes current-limited with voltages above 4-6V. At 15V VGS, the current passed is roughly proportional to the voltage applied up to 20-30V and 15-20A instantaneous current.
- The bottom line is it's best to use the highest voltage available for the gate driver (staying within MOSFET and gate driver specs, of course).
- Modulated Power (Zero to Three Channels)
- Maximum 80 V, 5.6A continuous
- Limited by the gate driver maximum MOSFET source voltage (VxHS), and the MOSFET voltage (VDSS) and current (ID)ratings.
- Modulated Ground (Three to Six Channels)
- Maximum 80 V, 5.6A continuous
- Limited by the gate driver maximum MOSFET source voltage (VxHS), and the MOSFET voltage (VDSS) and current (ID)ratings.
The current used by the timer circuitry is proportional to the voltage, so the power it needs increases by the square of the voltage applied. For example, if at 12V your timers draw 25 mA current and use 300 mW, at 5V they will draw about 10 mA and dissipate only about 50mW. At 80% efficient, a switching regulator will use about 60mW to deliver this energy. Further, since the gate driver will recognize a logic high for a voltage potential as small as 2.7V, if your 556 ICs will operate at such low voltage you can reduce the energy needed to run the timers using a 3.3V switching regulator to less than 30 mW, only 10% of the energy needed to run them at 12V.
However, be careful not to reduce the current consumption below the minimum needed to keep your regulator going.
Although most applications will draw timer and load power from one supply and a common ground, this board may be configured so the load and gate driver are electrically isolated from the timers by removing jumper JP1 (located on the skull's teeth). A separate MOSFET and gate driver ground VSS will need to be provided on the source pins of the low-side MOSFETs, and VDD (+7V to +15V) and VxHS will also need to be provided from isolated sources.
Mounting the Board
There are no mounting holes or other means provided for securing this board in place. You will need to think of something on your own.
Since this dual-555 astable/monostable PWM/PFM configuration cannot be adjusted to completely off or completely on (duty cycle 0% or 100%), it would be a good idea to use a three-position (xPTT) switch wired as off/on/variable. You could switch the load or use a logic-level switch off the jumpers in front of the gate driver inputs. You may also use the jumper provided for the gate driver's disable DIS pin.
There are many things you could do with this circuit, from the useful to the ridiculous. My favorite ideas involve mixing various frequency signals, capacitors, inductors, and transformers. Besides driving things like plasma balls, you may be able to make a pocket electromagnetic pulse (EMP) generator.
You will probably have to do some research to find the parameters needed to control a particular device.
- Muffin Fans
- The simplest way to configure this board for 12V muffin fan control in a computer case is to set the jumpers to power the timers from the 5V rail and configure all the MOSFETs as low-side drivers with all of them referenced to the common ground. The ground (black) lead on each fan goes into the drain connection on a MOSFET, while the power (red) lead goes to +12V as usual.
- Most computer fans are reported to prefer some frequency between 20 and 160Hz chosen by trial-and-error to minimize the noise produced. Caps: 0.1μF, Frequency Pot: 80kΩ-720kΩ, Pulse-width Pot: 10kΩ-450kΩ.
- DC Motor and Pump Control
- Most motors require frequencies in the kHz range. Do some research to get some idea of the operating parameters, then experiment to fine-tune your driver and perhaps test whether to use pulse width- or pulse-frequency modulation for the control you need.
- Electromagnetic Interference Generator (Jammer).
- Radiate a bunch of frequencies to create some interesting electromagnetic fields. Don't forget to take advantage of square wave harmonics!
- Automobile or Car Stereo Disabler
- This is more fun with EMI. The idea is to create a (preferably) directional pulse of EMR tuned or swept through common automotive or audio microprocessor frequencies.
- Electric Vehicle Power
- You should be able to get motor control with regenerative braking and PV battery charging with just one of these.
Here are still more ideas.
- How about a pocket arc welder?
- Electromagnetic Pulse (EMP) Generator.
- You should be able to make a mini-theremin using this.
- Control panel for boat or RV electronics
- Fish tank, homebrew, or rock tumbling systems control.
To get the most power out of your panel, it is likely to be worthwhile to use a 3-6V buck regulator to drive the timers, in addition to the 12V regulator for the gate driver.
Although standard photovoltaic (PV) panels nominally produce 16 to 18V (depending on construction), the actual output voltage can vary significantly with lighting conditions and temperature. A voltage regulator is strongly recommended to protect the gate driver when using standard panel. Nonstandard panels rated around 12V (xxx to xxx cells) should be safe to use unregulated.
If the voltage is reasonable, the raw panel power may be
modulated at 100-600Hz by one of the PWM drivers and used to charge a lead-acid battery,
adjustable from trickle to rapid charge.
You may also charge batteries with other chemistries if you know what you're doing.
The switching frequency [for NiCd/NiMH batteries is] (nominally 30kHz).
Using an external inductor, configure one MOSFET pair as a forward boost converter, and pass its higher-voltage output to the high side of the other MOSFETs. See Intersil's application note [AN9642].
Improvements and Design Changes
Most or all of the optional surface-mount components could be moved to the front of the board without too much tangly rerouting, but doing so might make it more difficult to build by hand. Also, this might require moving the ground and power wires to the top of the board, and the signals to the bottom.
- Add LEDs for a visual indication of the power level being delivered by each channel, and include one LED full-on as a reference. (Thanks [Darkcobra].)
- Add surface-mount pads for the gate driver components. This would likely require running wire jumpers among the source pins of the low-side MOSFETs.
- Add a fuse holder to the board, perhaps on the opposite side of the Molex power receptacle.
- Provide access to the timers' reset pins for external logic-level on/off control.
- Reconfigure the timers so each channel is driven by one '556 instead of half of two.
- Provide better access to the HIP4086 configuration pins.
- Add plenty of drawings and photos to this document.
Of course, it would be really nice to redo this circuit digitally in a CPLD, with quadrature-decoded thumbwheels and so on.
Since I haven't done PCB layout before and analog circuits are not my forté, I used quite a few resources to put this circuit together. Many of the files listed here were fairly hard to find, so I put copies of some of them on this server for your convenience.
- [ENTRY] Contest Entry Files
- The parts list is in HTML.
- The Zip Archive
contains the following files, along with all necessary
libraries and configuration files needed to generate the CAM files.
- Eagle Schematic pwfm556.sch
- Eagle Board pwfm556.brd
- The Zip Archive contains the Gerber files needed to produce this board.
- [HAD] Hack A Day
- All Contest Posts
- Contest Announcement
- Design Challenge mini-extra
- Design Challenge Prize update delta
- [TUTORIAL] PCB Design Tutorial Revision A - June 29th 2004, by David L. Jones
- This is a very helpful tutorial. The latest version can be found through www.alternatezone.com.
- [EAGLE] Eagle
- I used Eagle 4.16r1 for Windows Light Edition to design this circuit and lay out the PCB.
- [IC555] 555/556 Timer Resources
- [STM556] STMicroelectronics Datasheet NE556, SA556 - SE556 General Purpose Dual Bipolar Timers, June 2003
- [I555] Intersil ICM7555, ICM7556 Data Sheet FN2867.9, August 24, 2006
- [VROON] 555 Timer Tutorial, Tony van Roon
- PWM Fan Controllers, Dual-555 Circuit is part of a nice PWM tutorial using the same timer configuration. (I found this page after laying out this PCB.)
- NE555 and NE556 applications,Philips Semiconductors AN170, December 1988, is an application note with more information than most sane people want to know about the use of these chips.
- [HIP4086] Intersil Gate Driver Information
- Intersil Data Sheet FN4220.6, HIP4086
- Intersil HIP 4086 Application Note AN9642.3, HIP4086 3-Phase Bridge Driver Configurations and Applications, Feb 2003
- [MOSFET] MOSFET Information
- [IRF510]International Rectifier Datasheet, IRF510, PD9.325Q, undated.
- [TORRENS] MOSFET Testing, Richard Torrens, 2005, last accessed December 21, 2006
- [DIODE] Bootstrap Diodes
- The HIP 4086 Application Note calls for ultra-fast UF4002 diodes.
- [UF4002] Datasheet
- [DO-41] Finding if the diode package could be placed on the PCB with XXX″ pin spacing harder than it should have been. Here are two datasheets for the DO-41 package, XXX and XXX
- This is a typical potentiometer data sheet: Bourns 3362 - 1/4 ″ Square Trimming Potentiometer.
- [DIMENG] Dimension EngineeringSmall and Efficient Switching Voltage Regulators
- 1A Switching voltage regulator, 3.3 or 5V, 83% efficient, $15 [2006-12-14]
- 10W Step down adjustable switching regulator, 1.25 to 10V, ~90% efficient, $15 [2006-12-14]
- [CSIM] Online Circuit Simulator
- You can play with the timer components using this handy java applet.
- Open the Circuit Simulator Applet, choose from the menu, paste into the text field it presents the contents of this text file, and hit .
- [LEROY] Capacitor Design Data, and Decoupling Placement, How-to on Leroy's Engineering Web Site
- Decoupling and Bypass capacitors seem to be synonymous.