Electro Permanent Magnet View larger

Electro Permanent Magnet (replaced with newer version)


New product

Deprecated, replaced with V3R5C

This only exist for reference

The EPM688-V2.0 is an Electro Permanent Magnet, combining the advantages of electro and permanent magnets. Ideal for cargo clamping on UAVs like quadrocopters. With virtually no power during steady state operation (<1mW) and 600mA for 0.3s during a switch cycle. 

More details

More info

OpenGrab Electro Permanent Magnet

(Comes with one target square and 4x M3x0.5x5mm screws)


Git repository for Parts Drawing PCB Masks Pic12F source code


PDF Drawing

Shematics and PCB files

User Group (Help)


General Description


The EPM688-V2.X is an Electro Permanent Magnet, combining the advantages of electro and permanent magnets. This Device comes with integrated electronics that can be operated with 5V PWM signal common on RC electronics. The device is designed to hold 1kg of cargo. It is the user's responsibility to verify that this can be achieved in each particular case.


  • Robot arm work holding
  • Cargo lift for UAV's
  • Educational demonstration of magnetic properties
















  • CAN bus daughter card is available
  • 5V Vcc
  • PWM signal
  • Minimal steady state power <1mW
  • Water resistant conformal coating
  • 300ms Cycle times
  • On board Pic12F with source code and in-circuit programming header

Recommended Operational Conditions

Symbol Parameter Rating Units
Vcc max Power supply Voltage max 7 V
Vcc min Power supply Voltage min 3.3 V
Imax Maximum Supply Current 600 mA
PWM on Minimum signal high 1.75 ms
PWM off Maximum signal high 1.25 ms
PWM error PWM out of range <0.75-2.25< ms
Tmax Maximum Temperature 80 deg C
Tmin Minimum Temperature -40 deg C
Tcharge Charge time (1) 300 ms
Fmax Max holding force 60 N
Mass Mass 47 gram

(1) at 5V Vcc

CAN bus daughter card

OGCAN is an open hardware CAN bus interface that allows to control EPM and monitor its state via standard CAN bus or via serial CLI. OGCAN can be directly connected to EPM via two board-to-board connectors. Supported CAN protocols: CANaerospaceUAVCAN.

Learn more:


Pin Functions


Ground pin


5V supply <100mV ripple


RC PWM signal input


The Data pin puts out the current state of the EPM, TTL high for On and TTL low for Off.


These pins are broken out to provide the user with the ability to reprogram the on board PIC12F. Further information can be found in the documentation provided by Microchip.


After connection VCC and GND the device will start charging the main capacitor. This takes around 300ms at 5V Vcc. After the charge is complete the EPM is ready to go in either the On or Off state. After a command has been issued there is a 300ms delay before the next switching command is accepted to ensure that the capacitor is charged. When operating at low voltages care must be taken to allow sufficient time for the charging to complete.

Push Button Mode

Pressing the Push button will toggle the EPM

PWM Mode

A RC Pulse Width Modulated signal can also be used. High times between 0.75 and 1.25ms are consider an Off command. 1.75-2.25ms is considered On command. Moving the signal on time from neutral, 1.25-1.75ms to either On or Off range will command the EPM to go into the respected state.


The Led will blink once every 64 PWM signal errors. An error is either a missing or out time range PWM, about every 2 seconds for a missing PWM.


Led goes on when the button is pressed. The Led will blink rapidly 6 times after a command has been executed, either going On or Off.