HI, Just a quick one. I use 4QD speed controllers on my electric powered diesel locos and have found that they will take tremendous abuse providing a large Heat sink and cooling fan is fitted to the Mosfets. Regards Clif MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.