ante

audioguru vainajala, The collector outputs in the 494 can sink 200mA maximum, will this suffice as base current for three transistors? What makes you think that a Darlington can

Vainajala audioguru, I think it

Andy, The ATX main board or motherboard uses several different voltages one of these is +12Volts. Your computer won

vainajala, Try to use a 2.2k for R3. As far as I can see the emitters and collectors of the TL 494 is correctly connected. With the change of R3 the efficiency should improve a bit and the heat in R2 will be reduced. Have you access to a scope? I would be useful to see how Q1 performs and possibly make some minor changes to improve the efficiency. Ante ::)

Mixos, This is mounting to quite a library! Good Work! Ante ::)

vainajala, Looks very nice, please keep us posted! ;D Ante ::)

Laet, I suggest that you connect the rely on the other side of the transistor to start with. Ante ::)

audioguru, shekhar, I don

Laet, First, are you sure the coil resistance is 6.7 Ohms? This will be one HOT relay, nearly 30W it seems too much ???. Now that we know the purpose of the relay it

shekhar, What I mean is the length and the diameter of a cell. Ante ::)

Kain, Everybody makes mistakes sometimes, don

shekhar, You don

audioguru, I

Kain, With no external divider the 3V battery will show

Han, This is the easiest way I can think of, but maybe you had something different in mind? Ante ::)

Kain, Yes it

HAN, What kind of battery do you have 12V or 6V and what

Kain, There is one more thing to consider, these meters can usually not be powered from the same supply as you measure on. This is not a big problem, there are several ways to fix this. Ante ::)

HANIFF, Welcome to the community. I need to know some more details. What is the

audioguru, So that

Kain, Try to find the datasheet from your suppliers panel meters and study it. Most of the LCD & LED panel Volt meters have 199,9 mV, 1,999 V, 19,99 V, 199,9 V ranges. On the 199,9 mV range just shunt with a 0.01 Ohm resistor and your meter will show 0

Audioguru, What makes you think that a diode will slowdown the relay? And the cap is not supposed to be on the contacts but on the coil. Ante ::)

Kain, You can use a V meter as an A meter you just need a shunt. Ante ::)

Laet, audioguru, In fact there is a way without semiconductors involved! My first question was to establish if a cap over coil solution was right for this. If there is high current it will arc when the contacts open slowly as they do when the cap discharges. Maybe not to the eye but slow enough to burn the relay. My suggestion is to avoid semiconductors, find a small relay with high resistance coil and let the small one control the big one. This way the high amp relay will open at normal speed and no unnecessary arcing will occur. And no enormous cap is necessary. ;D Ante ::)

Laet, Welcome to this community. How much load are we talking about on the relay contacts? Ante ::)