LMH/ Texas Instruments Linear Voltage Regulators LMH/ Voltage Regulator datasheet, inventory, & pricing. The LM/LMC is a voltage regulator designed prima- rily for series regulator applications. By itself, it will supply output currents up to mA; but external. The LM is a monolithic integrated programmable voltage regulator, assembled in. lead dual in-line plastic package. The circuit provides internal current.

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My question is more to do with how the circuit itself operates because I’m not sure.

Power supply with LM – Electrical Engineering Stack Exchange

In non-experimental contexts they explode because a reverse voltage is inadvertantly applied across its terminals, or a very large current passes thru its terminals.

Oh man, can’t wait to read this. But, if you’d done that before working out how it worked you’d have learned far less: Q2 is a current limiter.

Most recently one of the transistors Q1 actually exploded on it. The current limit datasheeet crude in that it has no “foldback” action – it limits current AT 2A if you try to draw too much.

Q2 is for short-circuit protection- it detects the voltage across R Agreed – the inverting pin is fed by a very datasbeet arrangement – in fact that’s the exact part that confuses me besides the Vz being pulled to ground.


If you break this 3. However, it will only regulate a maximum output current of about milliamps. I suspect you’ll find a collector-base short on Q4. There may be other packages available from other manufacturers, but I limited my search datashet these three.

Voltage Regulator

I have also spent about half a day playing around with the various configurations on the datasheet to try and get a feel for how it works. The output of the ‘ is dahasheet pass transistor with the zener Vz pin 9 connected to ground, so that it pulls Vc pin 11 down in order to increase the output voltage. Secondly, apologies datssheet those who feel this question wasn’t researched enough nor novel. I have a basic grasp on their operation, getting more familiar with small signal characteristics, etc, but besides knowing the is the pass transistor and power transistor, that’s about it.

If the zener is not grounded it won’t work properly.

This is a design from the dawn of solid state time that has much to teach. Is Q2 providing feedback? This can be helpful if you are a beginner trying to decipher the terminology. I’d like to repair this but more than anything, I’d like to know what I’m doing rather than just plugging in components.

IF you want to abandon this cct but keep it working If you can tolerate 1.


The design followed relatiovely logically from what was available at that time. What’s the purpose of this? I’ve attached the circuit diagram. This is very much a design question and of great value to any who want to move beyond the “plug in a black box component” type of “design”. The negative Vout will of course not happen with a ground referenced positive input supply, but would be possible if Vin was referenced against some negative value. But again, all with certain limitations.

Email Required, but never shown. You mention 2N in comments but not on diagram or in question. Does it imply there are actually two transistors connected in parallel?

The LM’s primary intended function is to “regulate” a DC voltage. Privacy policy About OpenCircuits Disclaimers. It is designed primarily to be used as a positive regulator, but it can also be made to function as a negative regulator.

National Semiconductor

A will probably survive that if the heatsink is good enough. The metal can and the flat-pack do not have enough pins and so they skip this one. All the zener does in the diagram there is provide a stable voltage between pins 9 and 10, correct?