Switching power supply

[ante1]

vainajala,

Yes you have to arrange the supply and the TTL level for the input to use these drivers. The IRF9540N is a P-channel and it will work whit the MAX627. There are other MOSFET drivers out there just search for

 

[omiela]

am thinking of a device that converts pressure signal to radio for school project

vainajala,

Looks good to me, If you can fit a heatsink on the TO3 your home free. I can

 

[ante1]

Omelia,

Welcome to this forum.
It sounds like a strange device, can you explain a little more?

God

 

[vainajala]

Hello omiela

Is your project somehow related to this power supply?

 

[MP1]

omiela, please post with a new subject. We would like to hear about your ideas, but only those who are interested in the switching power supply will read this thread. Feedback will be limited.

MP

 

[Newguy1]

Hello every body
I have studied the 0-30 VDC STABILIZED POWER SUPPLY WITH CURRENT CONTROL CIRCUIT and discussed it with audioguru. I think that is a very good circuit.
However, if it can be realized by SMPS (switch mode power supply), it may be much lighter and the project may be challenging.
As a result, I search some circuits(P29-P54). But I don't know how to make these circuits to be variable voltage output with current limitation.
If u have any idea, please tell me, I am going to build this very soon.

Thanks!!!!!!!!

SMPS_POWER.pdf

 

[ante1]

Hi Newguy,

I don

 

[Newguy1]

Hi Ante
I mean P29-P54 of the attached pdf file. This file provide some circuit, but I don't know weather they can be adapted to be variable output.
I think it is not necessary to variable from 0V to 30V. Instead, it can vary from 3V-25V. Since I know it is hard for a SMPS to provide 0V.
And u can read page 53. This circuit uses the R5, R6 and TL431B to provide reference. Can I just simply change these three items to provide variable output?
Also can it be current limited.
Thanks very much

 

[ante1]

OK, page 29 to page 59 I get it. Are you planning to make a PSU without a

 

[Newguy1]

Hi Ante
Good.
I am going to build a power supply without transformer.
But I still have some problems
1. Like page 53, TL431B is used to control the PWM. Its voltage is 2.5V. What is the variable range of R5 and R6? How to calculate that? Also, how can I determine the output range of a circuit like that?
2. Also can u give me some ideas about adding the current limiter? I have little experience about that. What kind of current limiter? How to calculate?

Thanks very much

 

[Newguy1]

Hi Ante
Also, I would like to post my construction procedure of the circuit. But I don't know how to add photo to my message. Could u tell me how to make it?

Thanks

 

[ante1]

The TL431B can be viewed here: http://www.wb-power.com/bbs/u/20/1093886118.pdf If you f ex change R6 to 15k the output voltage will be 5Volts.

Just below the message window is the Attach window, here you can add your picture.

 

[Newguy1]

Hi Ante
Thanks for your reply.
Do u mean that I can vary the R6 from 15K to 75K.
But how about the current? How about the current limiter? ???

Thanks

 

[Bikerman]

Hello

I am on the lookout for a 12V 3,33A powersupply (for a TFT monitor), the one on page 54 looks almost simple, and it gives 3,5A 15V but that can probably ber changed easy. But what about the T1, there is no description of that? - or have I just missed it

another question is, if the TFT goes into power save or gets switched off, can the switchmode PSU deal with that?? (or does it need a minimum load?)

 

[ante1]

Bikerman, ...long time no

 

[Bikerman]

Yeah, been busy (got married and stuff)

on the last page of this post (page 3), there is a .pdf file called SMPS_POWER.pdf - with alot of examples of switchmode power supply's

 

[ante1]

Bikerman,

Got yourself a BOSS! Well, congratulations! ;D ;D ;D

About T1, I think you are right there is no description to be found here. Maybe an e-mail to onsemi will get you the data for the transformer. If you are lucky they might send you some samples of the MC33374 also. Please post the result if you get it the info.

 

[Alun]

Here's a very simple switching power supply I designed a couple of months ago to run 24V appliances of a 12V car battery. It's step-up only so it's probably of little for this application but if another coil was wound on to L1 thus converting it into a transformer it could be a step-up/step-down regulator too, current limiting might be possible as well. Let me know if you're interested.

Switch.pdf

 

[ante1]

Hi Alun,

Welcome to this forum.

Nice and simple DC/DC project with good documentation, thanks! With some small changes it might be possible to run a laptop in your car with it. Most laptops run at 16

 

[Alun]

Ante, you could power a laptop as long as it doesn't mind some noise and the the supply voltage going up or down by a volt or so. I believe most laptops these days have a built in voltage regulator to provide separate 12V, +-15, 5V & 3V supplies or whatever modern computers need.

One thing I tried in order to improve the efficiency (but it didn't work) was to substitute Tr2 with a power MOSFET and connect the gate to ground with a reversed diode to prevent it from being destroyed by the negative pulse. The circuit would oscillate at very low voltages (1 to 3V drawing an amp or more) and higher voltages the it would latch on. I tried altering R1 and C1 also replacing L1 and altering the numbers of turns on the driver and feedback all to no avail.

Does anyone know how to make a MOSFET blocking oscillator?