The fine wine preamp now available
Posted: Tue Jan 31, 2012 3:15 pm
Joe Jarski has done his part of this quite nicely (as usual - hat tip Joe) so now we can offer the fine wine preamps for sale. With slight component changes, these can handle quite a wide range of requirments. These are done so things like gain and low frequency rolloff are very easy to change, bias for different supply voltage ranges and speed are also possible to change, as is input impedance.
We can offer them in kit form, but unless you do SMD things a lot - they're not that easy to build, and we'll make them available built and tested of course - with any changes you need put in from the beginning.
Here's some documentation on these:
As shown, these are meant for 6v and up (tested to 15v but more is possible) power supply, positive DC. The input impedance is about 66k, and the gain is about 150 - too much for many phototubes, about right for most proportional tubes. Very easy to change that by changing one resistor, R6. The gain is the ratio between this and R5, within limits. The open loop gain is 900-something so at very high gains you'll not get the oversimplified theory number, quite.
Note, the 680pf cap on the "AC" input will NOT stand off more than maybe 100 volts. If you're coming in from something in the kV, use your own capacitor and the DC coupled input instead.
At very low gains you won't be able to get full power supply rail swings, but any gain over 10 should be fine there (why would you want a zero gain preamp?). This will drive 50 ohm coax cables very nicely, and is meant to be small enough to go right inside your sensor head for lowest input capacity and EMI. A filtered power output is provided to allow you to use that for a coax return if the sheild on the other end is floating - you get a little better power supply noise rejection that way, since our filtered positive rail is actually the input "signal ground". For those who are going to drive TTL type inputs, you can add the optional pull-up and down resistors on the output to make it want to sit at 5v, for example 100k pullup and 120k pulldown will get pretty close. This was designed to drive either an MCA or a standard CMOS input, like the extra one on our standard counter.
This is biased so the output rests right near the positive rail - it's meant for negative going pulses. If you need the other polarity, you could rebias it, but that results in pretty nasty power drain. The correct way is to flip all the transistor sexes, diode polarities, and the power supply.
And now that I have a neat schematic all nicely labeled, I can go back to the design thread and update it with actual part designators and make it more clear. Thanks Joe!
Sale price for these will be $50 + shipping, to cover NRE and building labor. Kits - inquire and we can work something out.
We can offer them in kit form, but unless you do SMD things a lot - they're not that easy to build, and we'll make them available built and tested of course - with any changes you need put in from the beginning.
Here's some documentation on these:
As shown, these are meant for 6v and up (tested to 15v but more is possible) power supply, positive DC. The input impedance is about 66k, and the gain is about 150 - too much for many phototubes, about right for most proportional tubes. Very easy to change that by changing one resistor, R6. The gain is the ratio between this and R5, within limits. The open loop gain is 900-something so at very high gains you'll not get the oversimplified theory number, quite.
Note, the 680pf cap on the "AC" input will NOT stand off more than maybe 100 volts. If you're coming in from something in the kV, use your own capacitor and the DC coupled input instead.
At very low gains you won't be able to get full power supply rail swings, but any gain over 10 should be fine there (why would you want a zero gain preamp?). This will drive 50 ohm coax cables very nicely, and is meant to be small enough to go right inside your sensor head for lowest input capacity and EMI. A filtered power output is provided to allow you to use that for a coax return if the sheild on the other end is floating - you get a little better power supply noise rejection that way, since our filtered positive rail is actually the input "signal ground". For those who are going to drive TTL type inputs, you can add the optional pull-up and down resistors on the output to make it want to sit at 5v, for example 100k pullup and 120k pulldown will get pretty close. This was designed to drive either an MCA or a standard CMOS input, like the extra one on our standard counter.
This is biased so the output rests right near the positive rail - it's meant for negative going pulses. If you need the other polarity, you could rebias it, but that results in pretty nasty power drain. The correct way is to flip all the transistor sexes, diode polarities, and the power supply.
And now that I have a neat schematic all nicely labeled, I can go back to the design thread and update it with actual part designators and make it more clear. Thanks Joe!
Sale price for these will be $50 + shipping, to cover NRE and building labor. Kits - inquire and we can work something out.