Staigen

Oh, you wanted a +12V to -12V converter! As Alun show you here, this is a simple one, but lack exactly center of the ground, and is not nessarily in many cases. But i would connect the positive terminal of the 100uF cap at ground instead of connecting it to the positive terminal. And use ordinary 555:s, not the cmos type. And, it can't supply much current! //Staigen

It's okay Alun, i also make mistakes, often much bigger than this, sorry if you felt jumped on, not my intensions //Staigen

Hi Yepp, but you also removed the current feed to the ic and it's ground! ??? The red circles you put on the schematic is for highlighting some of the components, i belive If you omit the current limiter, wich i belive you should not, you can also remove the 1N914 diode, but you have to do something to the errors in the output pass transistors stage, as proposed in the other thread. BTW, why two threads about the same thing? See the other thread! Be my guest //Staigen

Hi again Well, wich IC was used in the improved 0 to 30V PSU here on this site? I belive it can handle inputs down to its negative rail, but i am not sure about its output, hey, audioguru, this i belive you know? Because the OP-Amp used in the original schematic not can handle inputs down to its negative rail, the output can not go down to zero! But if you change the OP-Amp to one that can do that, the output also can go down to zero, but you also need offset null capabilly to achieve this with some accuracy. The OP-Amp also have to have capabillities to work near the negative rail on the output, otherwise the output of the PSU will not go down to zero. By having a tranny, rectifier and smoothing cap giving some voltages moore than 30 volts when loaded at maximum. //Staigen

I belive we came a little bit offtopic, hehe, back into the line again! ;D ;D //Staigen

Come on Alun, use your common sense, the project is not a PWM controller, its only a variable cmos oscillator, driving a power mosfet, thats driving a DC motor! It have errors, stating it is a PWM controller, amongst others. And the parts list states IRF511 or IRF620 and the notes says that the motor can draw up to the max current of the mosfet. //Staigen

Oops, replying at the same time ;D. Hehe ;D Also, if changing the IC, it must be a high voltage, tolerating moore than the voltage at pin 8! //Staigen

Hi there, both of you Wrong, if i do my math right, maybee i'm wrong, correct me if it is so! According to my math, the divider should be 2k to 1k, or, better up, 4k to 2k! Then you have 0 to 30 Volt out. Also, the resistor in the input rail should have a resistance about 1.3 Kohm. There are moore errors, the series pass transistors 2N3055 and 2N3053 dont have a resistance path from their bases to their emitters! Also, the 2N3904 can get a large negative voltage on the base! How are you planning to switch the input voltage to the rectifier? Observe, maybee you cant get 30 Volts out of this PSU, too low voltage on the input! Also i belive the IC is wrong here, it can not swing to the negative rail on its input, and i'm not sure on the output, also, it's a doubble OP-Amp! A single would be better here, with offset null and working at the negative rail capabillities! //Staigen

Hi there It depends on how much current you have in the "ground" terminal, and how much it can be tolerated to differ from exact center voltage. How much output do you have from the PSU? Voltage? //Staigen

Hi No, i havent seen this before, got me a good laughter :) :D ;D Yepp, across R2! Only 6 Volt for the gate? I havent read the data for the mosfet, but isn't that a little low? And the gate connected to a Cmos, dont they have drive capability on the low side a bit? And no stopper? :( :D //Staigen

Hi there Jherms, velcome to this board There are many ways to do this! We need moore input! Constant RPM? Constant torque? Proportional? One direction or both? Voltage? Current? Stall current? What is it supposed to do? Moore? //Staigen

Hi there joneLL Its the international(european?) way of typing values. ISO, i belive

Hi there alkv23 Well, what is it moore to say? The cap is a 20 uF capacitor, probably a El-lyt, but not necessarily so. Any sign of positive or negative connections? Red and/or black connection markings? Red and black conecting wires? Without a pic it's almost impossible to tell moore! :( I belive you made a typo error 20.0uf +/- 10&<-- Should be % instead //Staigen

Why didn't he write that then? //Staigen

No problems here, it must be internet or your ISP or at your computer! ;D ;D //Staigen

Hey Xoy, maybee i can help you a little :) But first you have to start up a new thread, you can call it Digital Stethoscope or something you like. Then we take it from there. //Staigen

Hi walid I got i good laughter when i saw the reply from waferstar :) :D ;D But, what type of if transformer is it? AM or FM? Transistor to transistor? IC? Detector or intermediate? Coming from a junked radio? Oscillator coil? You see, it is many questions. The numders are probably house numbers and are not easily detected. //Staigen

Hi there chasmith17, velcome to this forum About your question, no, not easily :(! But if you mean from a transformer, yes, its easy! If you have a transformer with only one secondary you can use halfwave rectifiers, just ground one of the transfomer output wire and connect diodes to the other and if you prefer a fullwave rectifier you must use a transformer with double the voltage and a centertap, just ground the centertap and connect the other two wires to a rectifier bridge. The negative output from the bridge is the negative rail and the positive output from the bridge is the positive rail. //Staigen

I also had this problem, two weeks ago, or so, but now it works okay again, it was mostly at around the mid of the day. //Staigen

Hey A copy of the TTL Cookbook would be nice to have! :) :D ;D //Staigen

Hi there Mine is also worn out a little :) //Staigen

Hi maverick366 I have the book, but it is a paper book. I can scan a few sides if you want! //Staigen

Btw I belive the tap was for the speakers common supply. No output tranny, cheaper, simplier and better! :) I can get you a simple schematic, if you want! //Staigen

Hehe Hehe, but i'm fatter than you ;D ;D //Staigen

And now i'm here again ?? Thank you :). Then we are about the same age ;D! //Staigen