1k views

### Lighting either of two LEDs, or none, based on digital input

I ran into a problem which I tought was extremely simple, and after giving it some thought for more than 2 hours I had to recognise it actually is quite complicated. The problem is the following: I ...
• 378
3k views

### Measurement of the beta of a BJT with a multimeter

When we measure the beta of a BJT transistor with a multimeter, which beta is giving us, the maximum, the average or the minimum beta and under what conditions of Ic and Vce? Thanks
• 227
5k views

### Op-amp voltage boost circuit : how does it work?

I want to boost the output voltage of op amp to a higher value. I found the conceptual circuit below online. I understand that Q1 and Q2 are used to provide the necessary supply voltage for the op-...
• 922
1k views

### Transistors on op-amp power rails

What is the advantage of using transistors on the power rails of an op-amp over more typical boost circuits? I have seen a circuit topology called the "Widlar Boost" made famous by Bob ...
• 9,209
262 views

### Current controlled bridge amplifier

This circuit essentially takes a control input and then doubles it when presenting it to the load. I would like a circuit that controls the current to the load. How would I modify the circuit to do ...
• 82.8k
796 views

### Voltage controlled current source using op-amps

I have a sensor which gives a voltage output between 0V and 5V. I need to transform this sensor output to a current suited for a 4..20mA current loop. The thing is, the current loop doesn't have a ...
533 views

### How can I get/build a current controller/amplifier?

Background: I have a Lorenz-actuator (coil+magnet) that I need to control precisely using a computer. The computer signal is output from a dSpace microLab box as an analog ±10V signal. This signal ...
1 vote
135 views

### Current mirror collector voltage

I'm trying to get the VGS of DMHC4035PMOS. Based on the simulation, I'm supposed to get -5.53V but I'm getting -8.2V on my PCB. Is there anything wrong with the design? What is the collector voltage ...
• 201
1 vote
104 views

### Feedback mechanism intuition

There is a circuit taken from the presentation below. Suppose at some point the VFM voltage rises from V0 to V0 + 0.01 V so V_minus of the op-amp rises too. So what causes the voltage on VFM to return ...
• 373
165 views

### Constant current source with high Vce voltage

At the moment I implemented a current source with two FMMT560 for about 1 mA. These types allow -500V Vce. I expect startup peaks of 520 V which is too much. Are there any current sources which use ...
• 141