voltage limiter designs

[windsox]

design for a voltage limiter. I was wondering what goes into a voltage limiter circuit. most of the voltage limiters I have seen are to big and heavy for my puposes. I wish to 2s lipos in my micro hand launch gliders but need to cap the voltage at 5 - 6 volts. I am pretty nieve in tgerms of electroinics but I take it a simple zenner diode is not going to be sufficient?

[Mr.RC-CAM]

Is this to reduce the Rx/servo voltage? What current?

RC-CAM

[ZAGNUT]

i'm going to lipo flight packs too but in bigger glow/gas planes. plenty of regulators out there but would rather have a simple DIY circuit. doesn't have to regulate either, just limiting the max. voltage to something safe would be fine.

how about 3 heavy-duty diodes in series? good or bad?


dave

[Mr.RC-CAM]

How about 3 heavy-duty diodes in series? Good or bad?
The issue with a simple series diode solution is that if you drop a 2-cell LiPO pack to about 6.0V at full charge, the voltage will be 3.6V when it is time to recharge. That is just not ideal. Even if the Rx still operates, the servo speed and torque is really goofed up. Unless this is for an indoor micro e-flyer, use an R/C Vreg.

[windsox]

this is for a sailplane. I have over a hundred tadiaran primarl lithium ion cells at 3.6 volts need to knock the voltage down to 5 . dont need low voltage protection. they are primary cells.

[Mr.RC-CAM]

For 2-cell operation you will need either a commercially produced R/C Vreg or you can build your own. For currents under 1 amp a heatsinked LM2940T-5.0 IC Vreg can be built (do NOT use a common LM7805 type). Takes two caps and the Vreg chip. Details are on the IC's data sheet as found on the Digi-Key web site.

RC-CAM

[Steph280]

What about dropping the voltage to 9volt for use on one of those ebay wireless cameras? Can similar circuit be used?

Thanks.

[Mr.RC-CAM]

Most of the eBay video systems need about 8V to operate. However, a dedicated 2S lipos might not work since the Tx freq will shift as the pack is used. A 3S pack with a 9V LDO Vreg would be best.

RC-CAM