Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Corwbar with LM723 triggered SCR

Status
Not open for further replies.

fjpompeo

Advanced Member level 1
Joined
Nov 29, 2003
Messages
407
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,296
Location
Brazil
Activity points
2,986
This is a new crowbar circuit at least to me, this application of the LM723 I've never seen before. This is a redraw of a Spanish magazine so I don't know about copyright it is just an amateur post. If someone have any observation against this circuit, please post it. In the article is said SCR activation time 1us or 2us too fast isn't it???
73 to all Fernando PU2PLL - Brazil
 

Attachments

  • Crowbar com LM723.png
    Crowbar com LM723.png
    13.2 KB · Views: 51

D.A.(Tony)Stewart

Advanced Member level 5
Joined
Sep 26, 2007
Messages
7,059
Helped
1,721
Reputation
3,441
Reaction score
1,716
Trophy points
1,413
Location
Richmond Hill, ON, Canada
Activity points
51,811
uA723 is an ancient Linear voltage regulator chip with many pins.

In this case the regulated Power Supply is external and just flows across the top 30A Fuse.

This circuit is a precision OVP or over voltage protection circuit that blows the fuse to probably a >300W power supply.

The chip uses a pot on the left to select the trip voltage of the output on top right. The OUTPUT is in the comparator loop while the VZ is the Output minus a 6.2V zener to pull up the SCR and blow the fuse. Since an old electrolytic cap opening up could result in Over Voltage Spikes ( or some other failure) which could cause other things to fail in the LOAD , the designer needed a really fast OVP., So he uses this precision SCR controlled fuse blower.

Not very elegant , but safe and effective.

This sounds like it came from a vintage 1978 magazine.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top