The ST and DT series of continuous ESD monitors are new and improved designs over the AEI-920xD series monitors. The new circuits allow for improved manufacturing and specifications while still providing low cost products. They also provide more trouble free operation with fewer false alarms due to operator movement and wrist strap handling. 

The ST series monitors are Single Threshold units like the AEI-920x series. They detect when the input at the wrist strap connection is above the high resistance threshold or above the body capacitance spec. The DT series monitors also detect when the input to the wrist strap is below the Low threshold.

Specification	AEI 920 X Series	ST Series	DT Series
Wrist strap high threshold resistance (alarms at):	7.2 Megs	10 Megs	10 Megs
Wrist strap low threshold resistance. (alarms at)	NA	NA	511 K
Bench Mat	10 Megs	10 Megs	10 Megs
Body Capacitance	180 PF	100 PF	100 PF

 NOTE: All threshold limits are +/- 10%