amp temp gauges

Hello Everyone, Its been awhile that I've been on the forum, nice to be back and do some reading. Ive got a question about the CyberDyne Amp gauges. Does anyone know if it would be possible to run a single gauge and two sending? with the sending units on a switch so i can monitor two amps with one gauge. I'm not trying to cut corners or cheap out, Its mainly to save the space of having two gauges to find mounting locations for. Id really prefer to have no gauges at all. Maybe just the digital readout that i could custom mount some place. wonder what the inside of one of those gauges looks like? anyone know? Thanks

the amp temp gauges post is mine. thanks&sorry

91' Nissan 300zx x/32

140 amp alternator1/0 Stinger HPM power WireStinger HPM RCA's (series 2) Pioneer N-3 DVD/Nav H.U.Diamond Audio Hex 6.5 components(silk tweet)(doors)Diamond Audio D-6 700.4(Bridged into 4ohms for 350w x2)Diamond Audio D-6 1500.1(Wired into 1ohm Mono for 1500w x1)2 Diamond Audio D-6 10's (sealed in two separate boxes)2 Pac CF-1 brushless cross-flow cooling fans

It should be okay with a good switch, else a small relay. The sensor is simply a resistance that changes with temperature though it could be a diode or other device (even a chip). [It looks like a single-wire connection - not 2-wires as used with thermocouples which have low signal power/voltage.] The gauge is merely a voltage meter calibrated for the resistance/temperature. The sensors are usually linear (that avoids the need for signal conversion - eg, PICs or analog circuitry) and sensors are usually matched (so that replacement sensors can be used without recalibration). There are cheap voltmeter modules (LED, backlit LCD etc) that have 200mV, 2V, 20V etc ranges (see eBay etc). It should be possible to make your own whether using a resistive divider (resistor &/or calibration trimpot between a regulated supply and the sensor; plus some sort of offset depending on the temp scale) or a temp sensor device like the LM335 chips (~$4; good to 200°C; search for its datasheet).     The LM335 (or similar) is good because of its accuracy and low impedance (hence not fussy re cable length or low quality switches) and circuit-wise, it looks like an ordinary diode (ie, GND one end; the other end to the meter). You could also use temp switches/devices ($1-$5) to signal an over-temp, but that may be better as an audible or visual alarm or kill circuit. That also provides independent redundancy.

I had an older version of the Jaycar unit - it was pretty good, though the new one had a digital readout of the car's voltage albeit unfortunately from the cig socket. But the external temp sensor is not unpluggable though I was considering adding a plug for it. I also suspect its range may be too low - amp heatsinks often get above 100°C. Since then I've integrated a 3-digit blue-LED voltmeter into my instrument cluster, and I bought several DMMs from Jaycar with temperature probes (up to 1,000°C) when they sold out for $10.50 each (normally ~$26). Not that they are easily hackable - pity - a nice backlit LCD albeit a bit big for my purposes. I'd probably try to find a suitable voltmeter module on eBay etc (typically under $10) and get a sensor. Alas my PC data & links are currently unavailable (thanks windoze for scrambling disks over 139GB if the appropriate W2k & XP patches aren't loaded and 48-bit LBA enabled - you recalcitrant bricks - no >139GB disks until w2k SP4+ and XP SP2+ !!!) and I'm currently imaging & recovering disk data (probably to no avail since it will probably just be junk) before I reload from backups...

Don't use any Swede to re-upholster - that's illegal - though IMO it should be ok if they are put down humanely before skinning (though I know a few Swedes where I'll gladly overlook that). Suede however is usually quite okay. Re your Lenovo, deleted files and reformatted disks can be recovered - except when overwritten with new data (though there are techniques to recover data that has been overwritten dozens of times). My software detects old partitions etc. It does recover files faithfully, but since that windows 48-bit LBA bug corrupts the file tables, the file table data does not map to where the files actually are. (I used to manually remap 1.4kB floppy disks, but since 140GB is 100 million times larger - and my corrupted disks are 750GB & 1500GB - I think I'll leave that till the weekend.     [ FYI - congrats - I never bother with emoticons/smilies! ] I might look into a sample 355 circuit tonite since I only have a few thousand other things to do. The Stinger voltmeter(s) may not be useable because they measure their supply voltage (and hence probably won't work below ~6V etc), though it is likely to be some "standard" voltmeter chip where they simply interconnect its sense wire to its supply (maybe thru a resistive voltage divider) and use a common ground. WARNING - if buying voltmeters, ensure that they can measure "common ground" (or "common reference") voltages. IE - multimeters (DMMs) are no problem because they have their internal supply (eg, a 9V battery) which is totally independent (aka isolated or floating) from the +ve & -ve that its input(s) are measuring. To use those DMM chips (voltmeter ICs) as a car voltmeter, they add an isolating dc-dc converter. (I know the reason is simple, not that I can recall that simplicity at the moment.)    Since your sensor will in some way be powered by your 12V system (hence referenced - ie, connected to it), you may need a certain type of voltmeter. Not a big deal once you know about it (since the dc-dc converters only add $1 or $2 to the price, but then are probably cheaper anyway because of their greater mass production (ie, universal application - it doesn't matter if the power supply is interlinked to the sensing voltage). But after checking the 335, I might check my sanity in this warning! BTW - suitable voltmeter modules are available here (Jaycar?) for ~$25 - $40 (~$10 - $20 for the non-isolated types), but as I recall, my blue-LED & my larger blue backlit LCD voltmeters were ~$6 & $10 each plus postage ($10-$20 LOL) from eBay (Hong Kong etc). Anyhow, if the Stinger's sensing pin can be disconnected from its supply, then it should be easy to adapt to the 335 or whatever temp sensor is used. Scaling is another issue, but probably solvable. (IE - is the Stinger set to sense 0-2V and then a 10:1 resistive voltage divider used to drop 20V to 2V (ie, 13.8V to 1.38V)? The DP (decimal point) position is manually configurable on the display (LED) so 1.38V actual reads as 13.8V. I hope that's the case because it means a "standard" chip etc, and greater versatility (eg, to measure a 200mV or 2V or 6V sensor etc). GEEZ I know this all sounds so complex, but it's because I/we don't know what we are playing with. Does the Stinger have a visible chip? Hopefully with a visible part number (spit-finger its surface if they have done a simple scrape-off job)? If it's a typical DIP chip (dual in-line package - eg, 2 rows of 7 or 8 pins) than matching should be easy. If its a round blob, then it gets tricky (but those car audio systems are usually SO primitive!) (I have a forum pic of one somewhere - it was on my PC... (but should be backed up somewhere...).) But with known components - eg, a 335 (or whatever sensor) and a typical "floating" voltmeter module, it should be fairly simple. IE - Connect +12V to the module. Connect the sensor to its input(s) with whatever resistor combination provides the correct readout. [ As long as you don't mind reading the temperature in °Kelvin. LOL! (I hope that's a LOL!) ] Next - fan speed controlled by temperature. (Yes - there is a perfect chip for that - not that I could source one when I wanted to use it as a LED dimmer, but apparently they are or were common in PCs etc.) Then - Peltier electric cooling, plus a nuclear supply to power the Peltiers. Or - finding out how wrong I am about the alleged "simplicity" of my solution to your original problem. (I got 1.5 hours sleep last night. And wow, 2 hours to recover a 16GB USB stick - and it's only 4/5th complete! Yep - my 1500GB disk could take a while...)

sorry about the link . im not sure what happend there.

ill try it again.

http://www.electronics-diy.com/pic_temperature_meter.php

You weasel! (LOL) But if that kit is ok... It is a nice kit and it includes the PIC software. If the software source code were available, then it could be extended for other sensors. The DS18S20 sensor(s) is pretty cute too. And it can still function as a 1-wire sensor (ie, like an LM335 etc - just one wire from the "meter" to the sensor with the sensor grounded). As to the LCD, blue backlits are available (from the same site, else eBay etc) and they could be substituted. Probably other combinations too - black on white, etc. The key is to look for the HD44780 compatibility - that's what determines the language/protocol that the LCD module understands. I though our DIY solution would have been ok (voltmeter with whatever analog sensors) though I haven't yet looked in detail. And that kit removes any need for offsets & calibration. Nice indeed!