The device is popular as a triggering device and is not suited for driving power loads. The device is preferred in other applications where guaranteed minimum pulse amplitude is required and also where a low emitter leakage current and a low peak point emitter current trigger current are required. In the above circuit we are working 2N as a relaxation oscillator to produce trigger pulses or oscillations. The capacitor C1 is for triggering the UJT and resistor R3 is for limiting the flow of charge to capacitor. The circuit is powered from single power source of VCC. When the power just turned ON, the UJT will be in high resistance state and total supply voltage appears across it.
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Last edited: Apr 15, Scroll to continue with content. It's commonly used as a trigger for an SCR or as a relaxation oscillator which is it's purpose in your application.
Here's an explanation of the device. Those things seem rare. As rare as Hen's Teeth. What would be a good substitute? Or what's the alternative for the circuit I've found? The list it an SCR but it's not. I was just looking at PUT's. But what has me confused is the "Programmable" part in the description. And I'm assuming the lead pin-out is the same as the UJT. What'cha all think? The PUT pinout is different from the original unijunction.
The G terminal has resistors connected to it to determine the peak voltage and current characteristics. Terminal A is the same as the original Unijunction E terminal. The K terminal is the same as the original B2 terminal and would go to the headphone.
Here's a typical circuit connection: It's programmable in the sense that you can change resistor values to affect the peak point voltage and current. You possibly can do that to match the characteristics of the 2n in the original circuit. No, an SCR is an entirely different animal and won't work in that circuit. Reading this data sheet may help. Bordodynov Joined May 20, 2, Bordodynov I struggle with LT Spice.
Can you show me Vb2 as well? It might help me understand how this device is programmed. Dodgydave Joined Jun 22, 9, Tonyr here is the same circuit If you use surface mount you can get both devices in a tiny 6-pin package. I can't remember what the thread was about, other than driving an optocoupler with very low average input current. GE Transistor Manual covers Unijunctions -. OBW Joined Mar 2, 3, Tonyr said:.
Holy Schmitt that's a big book. Regards, Dana. AnalogKid Joined Aug 1, 8, RichardO Joined May 4, 2, You must log in or register to reply here. You May Also Like. Continue to site. MEU22 Programmable Unijunction.
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