New Circuit Diagram 2 0 Beta 1 Released

This release includes a number of changes to make designing circuits easier, including automatic flipping of components when placing them and dragging from right to left or bottom to top. Documents can also be resized and there are many improvements to the use of keyboard shortcuts, including the ability to delete components by pressing the delete key on the keyboard.

Please see below for the full list of changes.

Windows Explorer Thumbnails

Thumbnails are now shown in Windows Explorer for Circuit Diagram Documents, as shown in the picture below. This feature has been difficult to get working, and there may be problems with the thumbnails not appearing - please leave a comment to let me know if they are working or not.

List of Changes

The following new features have been added since Circuit Diagram 2.0 Alpha 3:

• Automatically flip components when placing
• Delete components using keyboard delete key
• Resize document
• Document properties window
• Print document
• Recent files list
• Confirm when exiting with unsaved changes
• Thumbnail previews in Windows Explorer for CDDX files
• Show shortcut keys in toolbox
• Highlight selected item in toolbox
• Zoom using mouse scroll wheel while holding down ctrl key
• Plugin support for:
  • Custom export formats
  • Custom import formats
• Open CDDX files created in Circuit Diagram 1.x
• New components:
  • Voltmeter & ammeter
  • 4-bit counter

Please note that the .NET Framework 4.0 is now required.
You can download the new version here, and please get in touch using the forum if you have any questions about this new version. Link

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Simple 0 30 Volt Laboratory Power Supply

The linear power supply, shown in the schematic, provides 0-30 volts, at 1 amp, maximum, using a discrete transistor regulator with op-amp feedback to control the output voltage. The supply was constructed in 1975 and has a constant current mode that is used to recharge batteries. 

With reference to the schematic, lamp, LP2, is a power-on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, and Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zener across C2 limits the maximum supply voltage to the op-amps supply pins. D5, C4, C5, R15, and R16 provide a small amount of negative supply for the op-amps so that the op-amps can operate down to zero volts at the output pins (pins 6). 

A more modern design might eliminate these 4 components and use a CMOS rail-to-rail op-amp. Current limit is set by R3, D1, R4, R6, Q12, R10, and R13 providing a bias to U2 that partially turns off transistors Q9 and Q11 when the current limit is reached. R4 is a front panel potentiometer that sets the current limit, R22 is a front panel potentiometer that sets the output voltage (0-30 volts), and R11 is an internal trim-pot for calibration. The meter is a 1 milliamp meter with an internal resistance of 40 ohms. Switch S1 determines whether the meter reads 0-30 volts, or 0-1 amp. 

0-30 Volt Laboratory Power Supply Circuit diagram

 A more modern circuit might use a single IC regulator, such as the MC78XX, or MC79XX series, immediately after the half wave rectifier, to replace approximately 30 components, or at least a high precision zener diode to replace D10 as the voltage reference. The LM4040 is one such voltage reference and has excellent stability over temperature. IC regulators such as the MC78XX series may eventually become obsolete as newer IC regulators are designed, however, discrete transistors, op-amps, and zeners are more generic, have a longer production lifespan, and allow the designer to demonstrate that he understands the principles of linear regulated power supply operation.Link

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