 | | Help with converting voltage on circuit board —Dustin Jones
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| | | I'd like to try to convert the output of the voltage on a 9750 from 4V to 12V (to control 12V trains :). I've taken a photo of the internal circuit board - my rudimentary EE knowledge leads me to be believe I need to swap out the transistors that (...) (19 years ago, 7-Apr-06, to lugnet.robotics, lugnet.technic)
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| | | | | Re: Help with converting voltage on circuit board —Jonathan Wilson
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| | | | | (...) I am not an EE either but I can see at least 2 things that look like voltage regulators. (19 years ago, 7-Apr-06, to lugnet.robotics, lugnet.technic)
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| | | | | Re: Help with converting voltage on circuit board —David Wegmuller
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| | | | | (...) Hi Dustin, I am an EE. Before I give you some advice, I need a bit more information about 9750 (I have never seen one in person): - I see a power jack: I assume this powers the electronic circuit, not the loads, right? What voltage is applied (...) (19 years ago, 8-Apr-06, to lugnet.robotics, lugnet.technic)
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| | | | | Re: Help with converting voltage on circuit board —Danny Staple
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| | | | | (...) Wow - I remember those, we used them at school. Now why is it that Peeron do not have an entry for it under 9750? Those are also some big old capacitors, I would be inclined to check out their ESR (a rating of their health if you like) before (...) (19 years ago, 8-Apr-06, to lugnet.robotics, lugnet.technic)
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| | | | | Re: Help with converting voltage on circuit board —Dustin Jones
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| | | | I've taken some more detailed pictures of the circuit and the reverse side. (URL) through the manual, connections 6 and 7 are for sensors and connections 0-5 are for output (4V as labled on the cover), but you only can turn the circuit on or off. (...) (19 years ago, 8-Apr-06, to lugnet.robotics, lugnet.technic)
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| | | | | | Re: Help with converting voltage on circuit board —Philippe Hurbain
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| | | | | (...) The BDX34 transistor + toroidal inductor above + LM339 comparator probably compose a switching regulator efficiently converting 13V input power to 4.5V for the outputs. Philo (19 years ago, 8-Apr-06, to lugnet.robotics, lugnet.technic)
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| | | | | | Re: Help with converting voltage on circuit board —Danny Staple
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| | | | (...) Thanks Dustin, those will help. I am inclined to agree with Philippe Hurbaine on the regulator. It is also obvious that it can take AC from the full wave rectifier near the power port. In answer to Davids question about the 4v connector (using (...) (19 years ago, 8-Apr-06, to lugnet.robotics, lugnet.technic)
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| | | | | | Re: Help with converting voltage on circuit board —David Wegmuller
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| | | | (...) Hi Danny, If we supply +12V to the top of the transistors, the drive circuit will most likely not be able to block those transistors completely (unless said drive circuit has an open collector structure with a pull up to the emitter of the (...) (19 years ago, 11-Apr-06, to lugnet.robotics, lugnet.technic)
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