Any interest in a driver board?

[billm]

I recently acquired some solenoids that I want to drive with the MD24, but the solenoids work on 18v DC, at almost 1/2 Amp. I designed a simple circuit to drive all the solenoids, drawing only about 3 mA of current from each MD24 output. I also designed the Printed Circuit board to have a matching 26-pin connector (like the MD24 comes with), 12 sets of 2-wire jumpers (to drive the solenoids), and an input jack to connect to my 18v power source (an old laptop adapter).

Using different resistance values and transistors, this board could easily be modified to drive a wide range of devices.

The problem? Having 2 boards made (with no silkscreen) would cost about $98. Having 10 made drops the price to about $22 each, due to the large setup fee.

The components to mount on the board cost me about $30. That's 100 resistors (only need 48), the socket and cable to connect the boards, and 24 transistors. I would still need to buy the 24 2-pin jacks and matching connectors for the wires to go to the solenoid, and I already had the needed power supply.

So, my question is this: How much interest is there in this group for these boards? If enough people are interested, I'd place the order for 10 boards, and sell them at my cost, plus shipping. Post here if you would be seriously interested in these boards.

OR, if someone has already designed such a board, please let me know. Thanks!

[ranjit]

I hand-built a similar driver board using three ULN2803 eight-channel driver chips and -- nothing else, except a power jack for the solenoid power. It worked great, and not too much soldering. Total parts cost was about $5 for the prototyping board and $5 for everything else. It would be much nicer to have a printed board, though, and if anyone designs one, I'd buy some!

The ULN2803 can sink about 1/2 amp per channel, but only about 2 amps per chip, so there'd be a risk of burning out the chip if you frequently needed to simultaneously turn on more than four of your solenoids in the same group. I know I've gotten away with it for brief periods, though.

[kuchie]

I may be interested in a board depending on its design if youve gone to the trouble..... otherwishe i have been working on my own. How are you driving your outputs?

limits again with the ULN2803, i have moved forward to using the BD681 transistors for each channel, indicator led to show the output of that channel is turned on and a fuse holder for each channel. I have the whole design on paper but have had the best part of headscratching getting it into protel. I had problems with the library as mine is too old and have since started a desing in Multisim.

Mine was based on using a 24V DC input to drive 24 V lighting at approx 2A a channel (with heatsink) with also a small regulated circuit to reduce the power to feed the MD24

As i work 2 jobs im actually considering using the "press n peel" films and making the PCB myself like the good old days.

[davericebranson]

I'd be interested learn more about your board too. This is all a little new to me but I'm learning. I will need to drive L90 series F0464A solenoids for a rhythm section I'm beginning to work on (on paper for now). I also want to drive Stepper Motor (I think a: 42M100B321 Unpolar). The Steeper motor used for "Volume" control. I hope to be able to use one solenoid and one stepper motor at the same time for some of MSTA outputs. At least that's what I'm thinking now, but as I said, I'm learning.

Please let me know more about our board, when you are ready.

Thanks
Dave








I recently acquired some solenoids that I want to drive with the MD24, but the solenoids work on 18v DC, at almost 1/2 Amp. I designed a simple circuit to drive all the solenoids, drawing only about 3 mA of current from each MD24 output. I also designed the Printed Circuit board to have a matching 26-pin connector (like the MD24 comes with), 12 sets of 2-wire jumpers (to drive the solenoids), and an input jack to connect to my 18v power source (an old laptop adapter).

Using different resistance values and transistors, this board could easily be modified to drive a wide range of devices.

The problem? Having 2 boards made (with no silkscreen) would cost about $98. Having 10 made drops the price to about $22 each, due to the large setup fee.

The components to mount on the board cost me about $30. That's 100 resistors (only need 48), the socket and cable to connect the boards, and 24 transistors. I would still need to buy the 24 2-pin jacks and matching connectors for the wires to go to the solenoid, and I already had the needed power supply.

So, my question is this: How much interest is there in this group for these boards? If enough people are interested, I'd place the order for 10 boards, and sell them at my cost, plus shipping. Post here if you would be seriously interested in these boards.

OR, if someone has already designed such a board, please let me know. Thanks!