Hi!
can any body tell me if ther exists any switch which can turn ON and OFF 5 to 8 connections simultaneously(with single knob or slider), actually, I am making a JDM pic progarmmer and want to cut it off from serial prot by this switch , so if there is any such switch available then please tell me what is it called? And I also want to know that what are the percautions I should take to protect the MCU from electro static discharge?

 

Switches are electromechanical devices. There isn't one that will make/break 5 to 8 connections PRECISELY simultaneously without some kind of contact "bounce", sliding, etc. If you really need to make/break multiple connections at very close to the same time, you should look at using semiconductor switches - what kind depends upon what your signal levels and speed requirements are.

As far as ESD protection - keep your MCU "plugged into" anti-static foam, and in an ESD bag until you're ready to use it. Have an ESD mat at your workstation that is grounded. Use an ESD wrist strap connected to the same ground that your ESD mat is connected to. Beware of low humidity conditions. Avoid wearing clothing made of synthetic materials.

 

I suppose you could incorporate something like an 'LS623, which is a 3 state octal bus transceiver. Lots faster than a multipole switch. Not sure what you mean by "serial prot".

For ESD precautions, there is a long list. I don't think I have ever popped a chip, so I don't worry too much about it. If your circumstances put you in dry air and with lots of wool rugs around, maybe a conductive workbench top and wrist strap makes sense.

 

thank you both of you but, I want to detach JDM progarmmer( sch.attached) from a serial port of PC,now I can do that by simply pulling the serial cable out of JDM connector (I think that is what most people does , not sure!) but, I'm affraid that, it is possible that all the connection can not be braken at almost the same time as pulling out a serial port from it's connector is not an as easy job as a head phone attachement to a walkman. As the schematic shows there will be valtage level up to 13V your idia of using semiconductor switch was very good but, is there any easier idia, I don't want be lazy, just don't want to make circuit more complicated as I'm making it on a vero board,this is going to be much wiery!!

 

Get an RS232 switcher.

http://www.bb-elec.com/product_family.asp?FamilyId=102
Or the clunk-o-matic mechanical for way cheaper
http://www.cablesdirect.com/search_result3.asp?txtKeyword=DS_Serial&txtName=Serial RS232 Switches


You can wire those up so that it will switch out the programmer and switch in some other device or switch to nothing.

Or build one
http://home.teleport.com/~oldaker/RS232_switch.htm

 

An old PC on/off switch might work!

 

Or an old Data switch, the kind that routed 9 pin RS232 signals, already mounted in a box. Since they are obsolete I've been seeing for $3 lately.

 

Hey Bill,
I remember those But it seems to me they only switched the TX, RX and CTS/RTS signals - at least the one I had did just that. The REALLY old ones (that had DB25 connectors) probably switched more signals.

The parallel port switchers did a lot more pins. Those might be adapted.

I still have a switch kicking around that's designed to interface one keyboard, mouse, and monitor with up to four computers. They used to be around $25. Manhattan computer products distributed them.
Just found one listed; seems they've come down in price:
http://www.cablemax.com/show-item.cfm?id=151085&cat=MANUAL SWITCH BOXES&catlink=Switch-Boxes.cfm
They have DB9 and DB25 switches as well.