Al Heeley Posted December 16, 2011 Share Posted December 16, 2011 not so much an effect but a request for help - I want a small circuit i can put inside my gecko bass which checks battery voltage (9v pp3 drives the SD Basslines pickups) I have a small red LED which lights when the jack plug is inserted, its a sort of reminder to tell me its still drawing current. I want the circuit to kick in when the battery voltage falls below about 7.5v, so the LED doesn't light up any more. This will indicate to me when the battery needs changing. Any ideas? Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted December 18, 2011 Share Posted December 18, 2011 GB guitars have this on there basses. Something Bernie developed. When you plug the jack in a small light under the perspex control cavity cover flashes at a set pace. The light blinks differently when the battery is down to 10% or something. Very useful. Quote Link to comment Share on other sites More sharing options...
Dood Posted December 18, 2011 Share Posted December 18, 2011 (edited) I saw a bass once with a small LCD screen with the battery condition displayed on it. Being LCD, the current draw was so small a 9v battery would have powered it for years longer than in comparison to the draw of the preamp. I mention this as it could be something to take in to consideration. I'm not sure who produced the LCD, but certainly your idea is something I'd like in my basses. Edited December 18, 2011 by dood Autocorrect ruining my grammar! Quote Link to comment Share on other sites More sharing options...
RichF Posted December 18, 2011 Share Posted December 18, 2011 John East does a circuit that's on his website that only lights when the 9V is running out. Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted December 18, 2011 Author Share Posted December 18, 2011 I put together a little circuit last night that lights red when the battery falls below a set level - it has a mini trim pot so you can set the trigger voltage where you wish. [url=http://www.flickr.com/photos/alheeley/6525394351/][/url] I just want to take this one stage further to have a bicolour LED that stays green when the battery is above 7.5V, then goes red when below 7.5 to show the battery is running out. The 7.5 is my arbitrary level, you can set this at whatever is appropriate - just wait till your preamp sounds like its starting to break up, then check the voltage and set the circuit accordingly. One single bicolour LEd would be very unobtrusive on a bass body, and the current drain should be minimal. All I have to do now is figure out how to do it. Zener diode route is another (passive) option, but not fully figured that one yet. Quote Link to comment Share on other sites More sharing options...
Dood Posted December 18, 2011 Share Posted December 18, 2011 Al, that's really cool! Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted December 18, 2011 Share Posted December 18, 2011 [quote name='dood' timestamp='1324246378' post='1472284'] Al, that's really cool! [/quote] +1 Perfect it, then you can fit it to my basses Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted December 18, 2011 Author Share Posted December 18, 2011 cheers, got a mini push-switch on order, then you can just press the button to check battery state, rather than having an LED or circuit draining charge all the time. John East's little unit is far more elegant using a tiny pulse of light flashing when battery falls below the programmed level to stay economical with current drain, but this should fit the bill for my gecko. Quote Link to comment Share on other sites More sharing options...
RichF Posted December 19, 2011 Share Posted December 19, 2011 [quote name='Al Heeley' timestamp='1324249554' post='1472315'] cheers, got a mini push-switch on order, then you can just press the button to check battery state, rather than having an LED or circuit draining charge all the time. John East's little unit is far more elegant using a tiny pulse of light flashing when battery falls below the programmed level to stay economical with current drain, but this should fit the bill for my gecko. [/quote] that's a fab idea, and every bit as elegant as John's Quote Link to comment Share on other sites More sharing options...
Paul S Posted December 19, 2011 Share Posted December 19, 2011 And what we all want to know is, when will you start production!? Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted December 19, 2011 Author Share Posted December 19, 2011 bitsbox zener diodes with me tomorrow so probably about 6:20 pm Tues 20th Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted December 22, 2011 Author Share Posted December 22, 2011 (edited) OK here's mark III, uses a bicolor LED with common ANODE centre leg. 6.2V zener diode, 2 general purpose npn transistors such as 2n3904. Just double check the leg config if you're using a different type. One side of the LED will light up when the battery volts are above 6.9V, the other side lights up when battery volts fall below 6.9V. Get yourself a green/red bicolor LED and you are in business. Shove a small push-to-make test button on after the battery then you can quickly check your battery status between songs or gigs. [url="http://www.flickr.com/photos/alheeley/6554306733/"][/url] Edited December 22, 2011 by Al Heeley Quote Link to comment Share on other sites More sharing options...
TG Flatline Posted December 23, 2011 Share Posted December 23, 2011 [quote name='Al Heeley' timestamp='1324566125' post='1475683'] OK here's mark III, uses a bicolor LED with common ANODE centre leg. 6.2V zener diode, 2 general purpose npn transistors such as 2n3904. Just double check the leg config if you're using a different type. One side of the LED will light up when the battery volts are above 6.9V, the other side lights up when battery volts fall below 6.9V. Get yourself a green/red bicolor LED and you are in business. Shove a small push-to-make test button on after the battery then you can quickly check your battery status between songs or gigs. [url="http://www.flickr.com/photos/alheeley/6554306733/"][/url] [/quote] Nice! Quote Link to comment Share on other sites More sharing options...
geoffbyrne Posted December 24, 2011 Share Posted December 24, 2011 (edited) errrrrrrrrr........ how would this do for those of us who use 18V - or would it? (I know nuffing!!!! Nuffing!!!) G. Edited December 24, 2011 by geoffbyrne Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted December 24, 2011 Author Share Posted December 24, 2011 you'd whack in a much bigger resistor than the 10k one. Not certain of the actual calculations though! Quote Link to comment Share on other sites More sharing options...
MarkBassChat Posted April 20, 2012 Share Posted April 20, 2012 [quote name='geoffbyrne' timestamp='1324725892' post='1477326'] errrrrrrrrr........ how would this do for those of us who use 18V - or would it? G. [/quote]This is difficult since such professional circuits are built using micro-power comparators and they usually work only up to 12V. There are two workarounds: 1. monitor only one battery and assume that the voltage or the other one is simmilar. This is very good assumption since the current drawn from the second battery is the same as from the first one. 2. buy 2 circuits and monitor each battery separately. I plan to build such a circuit next month. If I get good results, I will present it here. Mark Quote Link to comment Share on other sites More sharing options...
MarkBassChat Posted January 5, 2013 Share Posted January 5, 2013 (edited) Now I think that for 18V (2x9V battery) it is better to have two circuits and monitor each battery separately. It's because of the fact that with this configuration you can use a new battery (9.6V) with older one (e.g. 8.5V). With one circuit monitoring 18V you would replace two batteries even if only one of them needs to be replaced. But the main purpose of such a circuit is to avoid battery replacement when it is not necessary. Here is the circuit I built. It consumes only 30 microampers when it blinks (when it's not blinking it's much less). It's due to the fact that it blinks only for few miliseconds within a second. It starts blinking when battery voltage drops below 8V. Edit: I'm not able to attach a picture of the circuit. There is something wrong with both basic and flash uploaders. I'm getting an error "No file was selected for upload" but the file is selected. It's in jpg format - I assume that this format is allowed. Mark Edited January 5, 2013 by MarkBassChat Quote Link to comment Share on other sites More sharing options...
pete.young Posted January 5, 2013 Share Posted January 5, 2013 As it seems to say everywhere else in the forum, the uploader is broken. Put your pictures on Photobucket or similar and include the IMG tag in your posting. Quote Link to comment Share on other sites More sharing options...
MarkBassChat Posted January 5, 2013 Share Posted January 5, 2013 Here you go: Quote Link to comment Share on other sites More sharing options...
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