Level Meter Circuits SPM-3 WG

Here are three circuits from the manual. The design is entirely on discrete devices like transistors, diodes and zeners. Studying these designs will reinforce your basics. It is easy to make things work with chips, you learn electronics only the old fashioned way, use NPN and PNP.

The SPM-3 is a broadband and heterodyne level meter whose frequency range is is designed for balanced 1 20 channel systems. It can be powered from a built-in rechargeable battery or from the mains.

Wandel Golterman Level Meter SPM-3 is a broadband and heterodyne level meter whose frequency range is is designed for balanced 1 20 channel systems. It can be powered from a built-in rechargeable battery or from the mains.

1) The voltage scales are only valid if the unit is switched to voltage level 0 dB – 0.775 V.

2) The symmetry of the receiver input is measured by connecting a choke in parallel to the input terminals a and b of the receiver. of the receiver. The receiver input is connected to the built-in resistor.

Z = 150 Q (or 135 Q, 124 Q). Between ground and center a transmitter is connected via Z /4 = 37.5 Q (resp. 33.7 Q, 31 Q).

The symmetry of the receiver results from the level difference of the level at the transmitter and the displayed level at the receiver.