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It might have been between 2.5 .. 2.8V, it was about a year ago when I did the measurements. So the circuit is not totally bad, only that a lot of voltage is lost due to the functioning of the transistors as emitter followers. So the brightness problem could be fixed by increasing the power...
You are right about the transistors running as followers. But if I remember correctly, the last time I did some measurements, the Vce of the T1 was about 4V and not 1.4V. This is why I think that the transistors are not properly biased.
The design was inspired from an application note from the...
The power supply should handle the current load - it is a switching power supply made with an LM2576 powered from a rather large transformer.
What I am worried about is that the transistors are not working at saturation. Do you think that replacing the 2N2907 transistors with an UN2003 would...
Hi Keith,
The role of R2 is to keep the T2 blocked when there is no signal coming from the IC2.
Can you please give me some suggestions of improvements? I believe that the transistors are not properly biased.
Thank you,
Florin
I have a setup with 6 large 7-segment common anode displays (TOS-40101BH - high brightness, 5 LEDs per segment) running multiplexed. The problem is that the display brightness is much lower than expected. I am using a ICM7228A display driver along 6 x BD677 transistors for driving the anodes and...
Dual supply
Hello,
I am trying to build a power supply with two inputs. I have built the attached schematic using an BC327 PNP trannsistor and an BAT43 Schottky diode. The resistors were 1k and 2.7k.
The problem is the voltage drop across the circuit (0.5V).
I think that if I use MOSFET...
Hello,
I want to build a dual power supply system and I have designed the following schematic. I want to know you opinion on this circuit.
The way I want it to work is: while there is power on the primary line (transformer) I want the second LM2672 to stay in standby, this is achieved by...
vga switch ic
I searched the net and found that some video boards have 5V on pin 9. Can anyone confirm this information?
Also, I want to know if it is required to switch the following signals: 6 Red return, 7 Green return and 8 Blue return, or, if it is ok to put them to GND (pin 5).
I...
vga switcher circuit
Thank you for your answer. I looked at CD 4066 and it seams to have a narrow bandwidth (40MHz), and I think that isn't enough for switching VGA signals. TS5V330 from Texas Instruments has 300 MHz bandwidth.
You said that I need to route only the RGB and sync signals, but...
I want to build a VGA switch for 2 video sources (PCs) and 1 monitor. The resolution is 1280 x 1024. I am thinking of using TS5V330 (5V, 300MHz) or TS3V340 (3.3Vm 500MHz). Which one would you recommend? Also, if anyone could give me a schematic, I wold appreciate. Thank you.
I want to build a system with a PIC (dsPIC) microcontroller that will capture images from a PAL video camera and write them to a SD memory card. I want to know if anyone built this or if it's possible. Thank you.
download winpic800 3.55
I am using WinPic800 3.55g. Now everything works just fine. I have built the board using another shematic than the one that I have posted here.
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