A new phenomenon of single- event upset is introduced. The transient signal is produced in the output of analog circuits after a heavy ion strikes. The transient upset can influence the circuit connected with the output of analog circuits. For example

the output of operational amplifier can be connected with the input of a digital counter

and the pulse of sufficiently high transient output induced by an ion can increase counts of the counter. On the other hand

the transient voltage signal at the output of analog circuits can change the state of other circuits.