Can I use an SCR such as BT151 or BT136 (or even a triac such as TYN616), to pass a high voltage(400V) high frequency signal (pulsed DC at 50KHz) for a fixed period? such as 1 second on, then off for another second, then on again?
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2 Answers
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No. The off time is not enough for the thyristor to turn off AND the rate of rise of voltage (dv/dt) is going to be high enough to turn the thyristor on even without gate current.
Both factors are too high for general-purpose thyristors by at least an order of magnitude.
Use a MOSFET, a BJT or an IGBT. Or even a relay.
answered Mar 3, 2015 at 13:26
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No SCR's latch on as long as there is a positive voltage difference across its anode and cathode
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\$\begingroup\$ Hi. Thank you for the quick reply. But wont the pulsed DC reach below the Vth for the SCR, so if I shut off the control pulse, the next time the pulsed DC reaches zero, the SCR should shut off? \$\endgroup\$– dynamagMar 3, 2015 at 8:33
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\$\begingroup\$ So it is the voltage source and the gate that is pulsed? SCR's are very slow at switching \$\endgroup\$– user16222Mar 3, 2015 at 11:07
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\$\begingroup\$ The voltage source pulses at 50KHz. The gate at 1Hz. But, like Spehro Pefhany said, I need to use MOSFETs. Thank you for your input. \$\endgroup\$– dynamagMar 3, 2015 at 16:41