MicrobeHunter.com Microscopy Forum

Yes, a rectifier, even just a Si diode, Great idea! A full bridge would drop the input voltage by 2 x 0.6v (forward Si voltage), making a commonly available 5v supply now appear as 3.8v at the LM317. This is just 0.8v above the target 3.0v LED voltage. I think the LM317 needs at least 1.25v above it...

I, like many other proud owners of Omax LED microscopes, fried my LED PCB -and more by plugging in a wrong voltage but plug-compatible wall-wart. omax_repair_fried_pcb_q1_sm.jpg Many OMAX scopes including my nice M837ZL series scope have a proprietary board DXL80D which is easily damaged by over-vol...