A circuit arrangement, wherein the circuit arrangement comprises: - a chopper control circuit configured to drive an electric motor, wherein the chopper circuit comprises a speed controller, a Schmitt-Trigger and a chopper switch, wherein the chopper switch couples in series a DC source to a winding of the electric motor, wherein the winding is further coupled in series to a measurement resistor, wherein the Schmitt-Trigger is arranged to receive a control voltage (V set) at a non-inverting input from the speed controller and a voltage drop (V i) at the measurement resistor at an inverting input wherein the Schmitt-Trigger is configured to output a first signal (V g), which activates the chopper switch in response to the voltage drop (V i) being lower than the control voltage (V set) minus a hysteresis amount and deactivates the chopper switch in response to the voltage drop (V i) being higher than the control voltage (V set) plus the hysteresis amount; and - a speed monitoring circuit, which is arranged to receive the first signal (V g) of the Schmitt-Trigger, wherein the speed monitoring circuit further comprises: - a circuit configured to generating a time-frame signal, which indicates when a time-frame of predefined length changes from an inactive state to an active state, and which indicates when the time-frame changes back from the active state to the inactive state; - a circuit configured to receive the first signal (V g) and detect chopper pulses in the first signal (V g); - a pulse counter designed to count the detected chopper pulses while the active state is indicated by the circuit for generating the time-frame signal; and - a circuit configured to at least one of output and evaluate a state of the pulse counter, after the inactive state of the time-frame has been indicated, further comprising a comparator, which is configured to compare a counting result of the pulse counter with a limit value and to derive from the comparison result an estimate of the current motor speed (ω). - a chopper control circuit configured to drive an electric motor, wherein the chopper circuit comprises a speed controller, a Schmitt-Trigger and a chopper switch, wherein the chopper switch couples in series a DC source to a winding of the electric motor, wherein the winding is further coupled in series to a measurement resistor, wherein the Schmitt-Trigger is arranged to receive a control voltage (V set) at a non-inverting input from the speed controller and a voltage drop (V i) at the measurement resistor at an inverting input wherein the Schmitt-Trigger is configured to output a first signal (V g), which activates the chopper switch in response to the voltage drop (V i) being lower than the control voltage (V set) minus a hysteresis amount and deactivates the chopper switch in response to the voltage drop (V i) being higher than the control voltage (V set) plus the hysteresis amount; and - a speed monitoring circuit, which is arranged to receive the first signal (V g) of the Schmitt-Trigger, wherein the speed monitoring circuit further comprises: - a circuit configured to generating a time-frame signal, which indicates when a time-frame of predefined length changes from an inactive state to an active state, and which indicates when the time-frame changes back from the active state to the inactive state; - a circuit configured to receive the first signal (V g) and detect chopper pulses in the first signal (V g); - a pulse counter designed to count the detected chopper pulses while the active state is indicated by the circuit for generating the time-frame signal; and - a circuit configured to at least one of output and evaluate a state of the pulse counter, after the inactive state of the time-frame has been indicated, further comprising a comparator, which is configured to compare a counting result of the pulse counter with a limit value and to derive from the comparison result an estimate of the current motor speed (ω).