This regulator is very simillar to mine. I can not find schematics for mine. One transistor is A1015, it is giving me -11 volts. The other is a C1815 it is giving about + 5.5 volts. There are no diodes on my board. Which leg of transistor should I follow? Does the "A" and "C" designate. EBC locations?
How does a transistor regulate voltage?
Thanks
Joe
How does a transistor regulate voltage?
Thanks
Joe
Attachments
Hi,
it's a transistor assisted Zener.
Output volts = Zener volts - Vbe drop of transistor.
Zener current varies due to the output pulling only a small change in base current. Therefore Zener voltage is fairly consistent.
I think there is no feedback in this circuit so it follows there can be no oscillation.
it's a transistor assisted Zener.
Output volts = Zener volts - Vbe drop of transistor.
Zener current varies due to the output pulling only a small change in base current. Therefore Zener voltage is fairly consistent.
I think there is no feedback in this circuit so it follows there can be no oscillation.
Transistor
I love this site. "3 seconds, politics aside....". That's very cool. Thanks for the help. I still don't get it but It'll make sense in a day or so. I have pulled all of the opamps and ICs , there are no zeners on this board so I am confused. What the heck is controlling these? I might wait a couple more days. I find when I patiently look at these circuits, I learn and get results ,which is happening. When I first started, I would recklessly probe, shunt and hardwire in attempt to make it work NOW. I did more damage than good.
Thank you all for education
Joe
I love this site. "3 seconds, politics aside....". That's very cool. Thanks for the help. I still don't get it but It'll make sense in a day or so. I have pulled all of the opamps and ICs , there are no zeners on this board so I am confused. What the heck is controlling these? I might wait a couple more days. I find when I patiently look at these circuits, I learn and get results ,which is happening. When I first started, I would recklessly probe, shunt and hardwire in attempt to make it work NOW. I did more damage than good.
Thank you all for education
Joe
Hi Joe,
As AndrewT suggested, it's only a transistor assisted zener diode. There is no feedback and therefore no active regulation.
What this does is reduce the current variations through the zener by the DC beta of the transistor. This is compared to the same thing using only a zener diode. Therefore the regulation, or variation of voltage caused by a current change is improved.
More complicated regulators use feedback to correct the output voltage. Voltage changes caused by current variations are reduced still further. Performance is greatly enhanced.
The main trick is to determine how much performance is needed. There is no advantage gained if the improved regulation from a more complicated circuit does not enhance the operation of the load, or circuit(s) that are powered from the reguator.
I don't know if that helps.
-Chris
As AndrewT suggested, it's only a transistor assisted zener diode. There is no feedback and therefore no active regulation.
What this does is reduce the current variations through the zener by the DC beta of the transistor. This is compared to the same thing using only a zener diode. Therefore the regulation, or variation of voltage caused by a current change is improved.
More complicated regulators use feedback to correct the output voltage. Voltage changes caused by current variations are reduced still further. Performance is greatly enhanced.
The main trick is to determine how much performance is needed. There is no advantage gained if the improved regulation from a more complicated circuit does not enhance the operation of the load, or circuit(s) that are powered from the reguator.
I don't know if that helps.
-Chris
I am so thankful for the help on this site. You guys probably love a challenge and would like to reverse engineer it. I don't have a camera here. I couldn't draw it because I need practice focussing. I get distracted easily and when I look at this PCB, my eyes go in to many directions. I am going to try one more time to get schematic. I would rather save your patience for other upcoming projects. I am a beginner and need alot of help. I will be back soon
Thanks
Thanks
The focus will come. I took a 6 month break from everything. I can't believe the way my head feels after working in the studio or on repairs. I feel like my brain has been doing pushups. I have only been using my brain for about two weeks now. It's pretty mushy. On the power supply topic...
I have two rackmount power supplies. One is a behringer Mixer Power supply(transformer, caps, resistors and regulator) The Other is a very complex looking setup(Kyocera) Stuck in a Dynamix rackmount case made to look like it goes with my mixer. I am not sure which one to use. The Behringer puts out 48V Phantom, 12Vdc aux, 5Vdc aux and +/-17Vdc. It is very versatile but I wonder about the quality. When using my mixer, I get a faint hiss during silence. I wondered if that was coming from PSU.
Back to the regulator.
In my synth I have some ICs that require +/-7.5 Volts. My kyocera has a +/-5vdc output. Would I have a better chance of testing ICs with +/-5volts than the present +5Vdc/-11vdc? What effect does difference on positive and negative rails have on IC function.
Thanks
I have two rackmount power supplies. One is a behringer Mixer Power supply(transformer, caps, resistors and regulator) The Other is a very complex looking setup(Kyocera) Stuck in a Dynamix rackmount case made to look like it goes with my mixer. I am not sure which one to use. The Behringer puts out 48V Phantom, 12Vdc aux, 5Vdc aux and +/-17Vdc. It is very versatile but I wonder about the quality. When using my mixer, I get a faint hiss during silence. I wondered if that was coming from PSU.
Back to the regulator.
In my synth I have some ICs that require +/-7.5 Volts. My kyocera has a +/-5vdc output. Would I have a better chance of testing ICs with +/-5volts than the present +5Vdc/-11vdc? What effect does difference on positive and negative rails have on IC function.
Thanks
Any effect, ranging from no power-on to explosion and anywhere inbetween.
Hiss from a mixer is in the mixer itself, most likely.
You can add another regulator stage to take the +/-17V to the lower voltage you need.
On a side note, regulated power supplies are pretty simple to put together and they can be pretty cheap with careful component sourcing.
Hiss from a mixer is in the mixer itself, most likely.
You can add another regulator stage to take the +/-17V to the lower voltage you need.
On a side note, regulated power supplies are pretty simple to put together and they can be pretty cheap with careful component sourcing.
AndrewT said:
Emitter followers with capacitors on the emitter are prone to rf oscillation, especially if you add capacitance from the base to ground.
You could also add a reverse polarised diode from collector to emitter to prevent reverse breakdown if the input is shorted while the output capacitors are charged
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