I'm raising funds for a short run of LF398 (Single chip Sample & Hold) PCBs. I've been having a blast with this chip, and you will too! The chip has built-in input and output protection for the signals, and the PCB includes a zener-based limiter to protect the Sample input as well. The whole project has 7 parts (that's including the DIP8 socket), and fits tightly on its 1" by 0.9" PCB. There are 4 mounting holes, though the PCB is happily supported by 2.
Here is a complete mouser parts list:
The goal of this kickstarter is to raise the $$ upfront to manufacture 50 S&H PCBs and ship them to you. This enables a virtually risk-free pre-order process. If not enough people want them, no money changes hands, and I try again! Otherwise any demand can be met as the rewards pay for the manufacturing and shipping of each board or kit.
The rewards are the PCBs. I'm offering bare boards, kits, and assembled boards (fully tested), as well as some fun perks (check the rewards to the right.) The PCBs have 4 mounting holes in each corner, compatible with standard 4-40 standoffs. The rows of pins on the left and right edges of the board are also compatible with 5pin 2.5mm pitch (0.1in) pin headers (my favorite way to mount!). The easy way is to attach 5pin female headers to the top of the PCB, and 5pin male headers to the back of the another PCB you want to mount it to, so that the two boards form a "sandwich". No wires, very clean.
The signal in, logic in (trigger), and output pads are labelled and have square ground holes next to them, for easy wiring to jacks.
The Kit Includes:
- 2 x 0.01uF bypasscaps
- 1 x 0.1uF polypropylene hold cap
- 1 x LF398 Monolithic Sample & Hold IC
- 1 x 1k Resistor
- 1 x 5.1V Zener (1N4733)
- 1 x DIP8 socket
Here's a pic:
It sounds like:
Sample in: pin 8 of LF398, input for trigger to sample or hold.
Signal in: pin 3 LF398, input for signal to be sampled/held.
Signal out: pin 5 of LF398, output of S&H.
note: samples are a bit loud.
Clock to sample in, slow lfo to signal in, output to fm in of resonating vcf (res up, no sig in). Listening to vcf out.
Clock to sample in, medium lfo to signal in, output to polarizing mixer, inverted output to vcf fm, non-inverted output to vco fm (vco into vcf as well) Listening to vcf out.
The last one is a little weirder...
Vco's triangle output to sample in, voltage sequencer to signal in, output to polarizing mixer. Inverted output of mixer to vcf fm in, non-inverted output to to vco (same as first) fm in. Vco's square output to vcf signal input. Listening to vcf out. So once per cycle, the sequencer is sampled and updates the frequency of the filter and vco, which plucks the filter for sine blips.
Meaning greater than S&H. Here are some ideas for other circuits that these boards/kits will support:
- Put multiple units in series, sending the odd units and even units alternating clocks to create an Analog Shift Register. Feed the end back the beginning for an Analog Voltage Looper.
- Put a pot or resister in parallel with the Hold Capacitor to create a Sample & Decay.
- Add a DC voltage via a resistor to the Hold Cap pin on the IC (pin 6) to create a Sample & Ramp.
- Replace the Hold Cap with a second signal via a resistor to create a 2-way switch (5v on sample in selects first signal, 0v selects the second)
Manufacturing & Assembly:
PCBs are from www.iteadstudio.com. They are in China, have wonderful customer service, and consistently provide excellent quality. The PCBs are ROHS compliant with solder mask and silkscreen. I'll be assembling the boards myself in my home in Austin, TX.
I think Kickstarter is a great way to do small runs of pcbs or other DIY synth projects. It supports Kickstarter (a rad concept and awesome implementation) and allows people like me to provide fun projects without tying up my limited funds. This small run is a test to see how well the community (you!) responds to this method, and its success will pave the way for much more demanding ($) projects in the future. We (pheops, Ianues, and executiveBlaster(me!) on muff's) are working hard on some really fun stuff, check our posts there!
Minimal design is my focus. I decided to pursue electronics and engineering because I couldn't afford any gear, so I try to make every project (and soon, products) as cost efficient as possible. It's my dream to help the joys of DIY electronics, synthesizers, math, art and nature become commonplace.
These S&H PCBs are not only a test of how appropriate Kickstarter is for synth DIY, but the first in a long family of tiny, minimal, DIY friendly analog synth circuits. Stay tuned, friends.
US shipping is built in to the price! If you're outside the US, please add $4 when you check out. ($4 per order, you don't need to add it for each individual reward)
Risks and challenges
The risk in ordering PCBs is always that no one will buy them, and you'll be out the dough you put up for an order. They're only cost efficient if you buy in bulk, so kickstarter is an important layer of protection for myself, and for you! In designing these PCBs (and any PCBs for that matter), the challenge is to provide not only a safe product that does what it claims to, but does what it claims to well. I've been building synth guts and servicing equipment (keyboards, appliances, a potter's wheel!) for ~6 years, and make my living designing custom audio hardware and software. I've thoroughly (and happily!) tested this circuit, and am happy to provide the opportunity for all of you to enjoy it, too.Learn about accountability on Kickstarter
- (9 days)