According to an author, the bridge rectifier needs to withstand the peak AC voltage + 20% headroom.
So a bridge rectifier for GM-70 needs to handle 34V Peak Reverse Voltage.
Can this rule apply with Schottky rectifier ?
So a bridge rectifier for GM-70 needs to handle 34V Peak Reverse Voltage.
Can this rule apply with Schottky rectifier ?
Thanks for the input.
Yeah the author states at least 20% more than the peak AC.
How much head room for current ?
Yeah the author states at least 20% more than the peak AC.
How much head room for current ?
Can I buy Schottky rectifier in a complete bridge unit with 4 terminal ?
I looked on mouser under "Schottky rectifier" and the only parts that showed up are just diodes that have two leads like a resistor.
I looked on mouser under "Schottky rectifier" and the only parts that showed up are just diodes that have two leads like a resistor.
At least double the current needed - ripple current in filter will nearly double RMS current. There are duals, three possible configuration - common anode, common cathode, doubler. Doubler or series configuration is best since two will make a bridge. You MIGHT find some leaded ones in singles - duals will be 3-lead, probably TO-220 package. You'll need a heatsink, can use chassis if you insulate it.
4X Mouser stock # 621-SBL1050 will do the job. That is a 10 A./50 PIV part. 😀
As Mr. Bavis said, mica washer insulators between the TO220 case parts and the chassis will provide all the heatsinking needed. Use nylon screws and nuts. Don't forget THIN heatsink compound layers.
As Mr. Bavis said, mica washer insulators between the TO220 case parts and the chassis will provide all the heatsinking needed. Use nylon screws and nuts. Don't forget THIN heatsink compound layers.
In a rectifier bridge, you'll need to have diodes that can withstand twice the peak AC voltage. So Vr(min) = 2*sqrt(Vrms).
The RMS current through each diode depends on the conduction angle, which depends on the reservoir cap and the load current. I generally find that the easiest way to figure out the current is to set up a simulation in PSUD II or LTspice.
~Tom
The RMS current through each diode depends on the conduction angle, which depends on the reservoir cap and the load current. I generally find that the easiest way to figure out the current is to set up a simulation in PSUD II or LTspice.
~Tom
Tom, I think you have mixed a 4 diode bridge up with full waved center tapped. In a FWCT setup, the diodes have to stand the end to end voltage of the rectifier winding. OTOH, in a bridge setup, the current always passes through 2 diodes.
Actually, if you are going to "filter, then regulate it", I seen little to no reason to use Schottky diodes to begin with. You'll definitely be inserting a snubber resistor before the first reservoir cap ... and the voltage drop isn't of concern, if you're going to regulate anyway. That regulator acts like a "power supply super-muffler", isolating whatever things that are before it, from that which follows.
GoatGuy
GoatGuy
One place you really do need to use schottky. Many old power transformers have a 5V winding for the tube rectifier heater. I've often used SS rectifiers for the HV and then you can get additional heater supply by Schottky Bridge Rectifying the 5V winding. With a decent size filter cap (say 10,00uF) and with 1 Amp draw you end up with 5.95V DC, close enough to 6.3V. Ideal for those preamp tube heaters.
Cheers,
Ian
Cheers,
Ian
Do you want SS diode switching noise sneaking into a power trafo that has multiple secondary windings sharing a core? When it comes to noise, less is ALWAYS more.
Also, as Ian pointed out, the forward drop in Schottky diodes is less than that in PN junction parts. That reduced loss can be the difference between success and failure.
I used SBL1040 in my GM70 amp. Ripple current is 6A, so they need a good heatsink!
The transformer winding is rated 8A, and it still gets a little hot.
The transformer winding is rated 8A, and it still gets a little hot.
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