Old Spring Line - what to do with it .

[nick d]

               I acquired it in the early 80s , recently unearthed it during an attic clean-up . Also , among the stuff gathered over the years is an old copy of Everyday Electronics , featuring a constructional article showing what looks like the same spring line . Having recently become a born-again stompboxer , I fancy having a go at this .
                The unit measures 30mm x 53mm x 205mm (exc. mounting ears )
                 D.C. resistance 1.6 ohms input , 917 ohms output
                 The article describes this as "Medium Spring Line , available only from Maplin " ( yes , really !) with impedances of 16 ohms in , 10k out .
                  It has 2 springs and is in good condition apart from the foam rubber , which has long since turned to dust .
                  The schematic is very simple , tranny input buffer , LM 380 N power amp , tranny output amp/mixer stage .

                 Looks pretty straightforward ( that's asking for trouble ! ) - my only query is :- would an LM 386 N-4 be suitable as a driver amp , 'cos I've already got some .
                   

                 If anyones interested , I could have a go at posting some pics - don't actually know how to do this , but I can try .

                  If anybody asks my age , I will reply " over 21 " !

[Top Top]

I have used a 386 to drive a guitar amp style spring tank before. It seemed I was distorting the chip to get a good loud level going into the tank, but I didn't spend a whole lot of time tweaking it, I just wanted to see if it would work, which it did on a basic level.

I've been meaning to try it again as it seemed it could have potential.

[maarten]

LM 380 is 2,5 watts, your LM 386-4 is 1 watt. Could be done, but might be insufficient powerfull fot a good sound. Maybe use the 386 to drive a pair of transistors for more power. I think I have seen schematics for that on the web.

               I acquired it in the early 80s , recently unearthed it during an attic clean-up . Also , among the stuff gathered over the years is an old copy of Everyday Electronics , featuring a constructional article showing what looks like the same spring line . Having recently become a born-again stompboxer , I fancy having a go at this .
                The unit measures 30mm x 53mm x 205mm (exc. mounting ears )
                 D.C. resistance 1.6 ohms input , 917 ohms output
                 The article describes this as "Medium Spring Line , available only from Maplin " ( yes , really !) with impedances of 16 ohms in , 10k out .
                  It has 2 springs and is in good condition apart from the foam rubber , which has long since turned to dust .
                  The schematic is very simple , tranny input buffer , LM 380 N power amp , tranny output amp/mixer stage .

                 Looks pretty straightforward ( that's asking for trouble ! ) - my only query is :- would an LM 386 N-4 be suitable as a driver amp , 'cos I've already got some .
                   

                 If anyones interested , I could have a go at posting some pics - don't actually know how to do this , but I can try .

                  If anybody asks my age , I will reply " over 21 " !  Probably over 51 as well??

Maarten

[nick d]

                     Thanks for those pointers , guys . Makes sense , a lot of people use 386's  in distortions , obviously for a good reason .
                      I'll go for the 380 , cost is not much more , and I think I might just have 1 or 2 if I dig around .
                     I'll let you know !

[nick d]

                  Just got this up and running , used an LM380 . The results , not impressive - to drive the spring hard enough to get a decent output gave a horrible distortion when hitting the strings anything like hard . Could work on a better recovery stage , but not really worth the effort right now .
                   Anyway , it cost practically nothing , and I learned a bit , so not a waste of time - thanks for the help , guys !