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Use BS2 to switch 12V circuit — Parallax Forums

Use BS2 to switch 12V circuit

qxoticqxotic Posts: 47
edited 2012-12-20 12:20 in BASIC Stamp
I am using a K80 Power Supply Control to energize an electric latch (Adams Rite 7100-310-628.. 12V .332 amp.. but the K80 relay supplies this power) The Power supply control has a ground and a push connection used to connect a push button to and activate the lock. There is a 12V potential across the PUSH and GND, only a momentary connection is needed because the K80 has a timer built in to it that keeps the lock open as needed. Momentarily using a wire to connect PUSH and GND makes it work.. as does using a resistor. I have used a 4.7K.. it works but have to touch it just right or longer sometimes it seems.. a 2.2K resistor across PUSH and GND works great just by tapping the terminals.

Given these details.. is there a good safe way to switch this using my BS2 with either a 4N29SD Fairchild Opto or a radio shack transistor?

I've done several forum searches and read some Nuts and Volts articles but did not glean an answer I am confident with.

Thank you all for your input.

Daniel

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2012-12-20 10:09
    Look at Nuts and Volts Column #6. It shows how to use a switching transistor to turn on a (relatively) high current or high voltage load like a motor or solenoid or relay. In the article, the transistor connects a 12V load to ground ... just what you need. You probably don't need the diode shown because you're activating the timer in the K80, not a relay or motor. RadioShack carries the parts needed.
  • qxoticqxotic Posts: 47
    edited 2012-12-20 11:50
    Mike, were you referring to figure 6.3? It shows a 390 R to base of transistor .. emitter to ground.. collector to 12V?

    Since the switch activates using a 2.2K R, would it be a good idea to use one between 12V (Push) and collector.. then emitter to GND on the K80?

    Thank you,
    Daniel
  • Mike GreenMike Green Posts: 23,101
    edited 2012-12-20 12:14
    Yes. Figure 6.3
    Yes. A 2.2K should work fine. A 1K will do as well and anything in-between. This looks like a switch closure input (to ground) and probably has its own resistor internally. Use a 1/4W resistor if 1K.
  • qxoticqxotic Posts: 47
    edited 2012-12-20 12:20
    Thank you Mike.. will do. That's what I was thinking but wanted to be sure.
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