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I want to make a circuit which can switch between -48V and 0V by applying TTL Signal. So if anybody has circuit or any suitable idea to do that then please must share it
You can do it using an optocoupler, connect the input to the diode and then the gnd to the collector of the optocoupler NPN and the emitter through a resistor to the -48 (emitter as output).
You will not get exactly 0V because of the Vce saturation but you will be very close.
The TTL signal shouldn't too much of an issue. For the 48V relay switch you might want to try: **broken link removed**. Is it for a LAN driver circuit. Do be careful of the current limits. Also, for conversion to TTL i.e. level translation, you can use a buffer for converting logic levels plenty around e.g. CD4504 (very old, try a newer one) be careful of current specs.
As mentioned in the post below: Since you need a -48V you need a dula polarity power supply circuit : a simple design for that is **broken link removed**. You can change the the resistors and caps to get 48V and use a LM137 instead of the LM337.
The TTL signal shouldn't too much of an issue. For the 48V relay switch you might want to try: **broken link removed**. Is it for a LAN driver circuit. Do be careful of the current limits. Also, for conversion to TTL i.e. level translation, you can use a buffer for converting logic levels plenty around e.g. CD4504 (very old, try a newer one) be careful of current specs.
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