<types. The replacement transistor <that NTE had didn't seem to have enough gain. In order <for a flyback switcher to work, the edges have to be sharp. <I currently have a 2N4401 in there but it may have too much gain <or not be able to handle the higher reverse voltage on the the 4401 is a good match but the NTE part should work. The transistor should be able to withstand 60V and have a moderate beta. I'd try a 2n2219 or maybe a 3904. The cicut is not the best design and tended to flake out if the load was too high. Allison